Any geniuses here?

I need help with my SAT prep class. I'm usually good with word problems but these have me stumped. Please just help me through them, I don't need the answers. This is an online class and I do not want to cheat! :) :p

Three years ago Bob was twice as old as Adam will be four years from now. Adam is "a" years old now. What is Bob's age in terms of Adam's age?
HELPFUL INFORMATION: Let a = Adam and b=Bob and let's write the equation as it is described b-3=2(a+4) then solve for b-Bob
a. 2a+6
b. 2a+11
c. a+4

If it takes p pounds of fertilizer to grow r rosebushes, how many pounds of fertilizer are needed for m rosebushes?
a. (rm)/p
b. r/(pm)
c. (pm)/r

Five books cost d dollars. How much money in cents will 7 books cost?
a. 7d
b. (100d)/5
c. (700d)/5

1. Well you know that Adam's age (a) is TWICE the amount of Bob's age, plus eight. So if Adam is a years old, you will need to multiply it by two and add eight :)

2. noooo friggen clue. I know it has to do with ratios but without a number I can't get it LOL

3. If five books cost D dollars, then you would find it easier to find out how much EACH book cost, so you would need to divide d / 5. Then after you find that price, you can multiply it by seven. :)

I hope I helped without giving too much away... :( Because GOSH its been years since I've taken any math classes LOL

I just did what you said and re-submitted and got the answers for all three wrong again :mad: :o :( Oh, and when I say this, I'm not mad at you LOL. I'm just frustrated.

SO, I'm going to edit the post with the remaining three answer choices and wait for more people to reply. I only have one more submission.

Well I can tell you the answer to the first and last one and then maybe explain to you how I got it??

b-3=2(a+4) then solve for b (I'm not a genius, but have had algebra recently)

Distribute first, so:
b-3=2a+8

Get b alone by adding 3 to both sides:
b=2a+11

I'll try more if you are still stumped, I am eating dinner right now.

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Originally Posted by Jessika

Well I can tell you the answer to the first and last one and then maybe explain to you how I got it??

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Okay ;) :)

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Originally Posted by boscibo

b-3=2(a+4) then solve for b

Distribute first, so:
b-3=2a+8

Get b alone by adding 3 to both sides:
b=2a+11

So for the first question b. is the answer. I'll try more if you are still stumped, I am eating dinner right now.

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Ah, thanks! I didn't do the distributive and that was the problem.

I edited out the answer I had posted, I didn't read you didn't want the answer!

The answer to the first one is b=2a+11. Simply just solve for b. They give you b-3=2(a+4). Add three to both sides to get b=2a+8+3. Add together and get b=2a+11.

The second one, you could set up as a ratio. p over r (it takes p pounds to plant r rosebushes) equals x over m (x number of pounds to get m number of rosebushes). So it should look like p/r = x/m . Cross multiply (p times m and r times x) and you will get pm = rx. Divide by r and get (pm)/r.

Third: Like Jess said, divide d by five, and you will get d/5. Then multiply by 100 to get the cents. You would get 100d/5. That is the price in cents for ONE BOOK. You need SEVEN. So you will multiply by 7, and get 700d/5.

Quote:

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Originally Posted by boscibo

I edited out the answer I had posted, I didn't read you didn't want the answer!

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It's fine. What I didn't want was someone posting only the answer. Even the tutors and teachers would explain it and most likely give the answer ... it's just too late to call them now ;)

ok well you already have the first, so here's the last:

(d/5) x 7

BECAUSE:

you need to find out the price for each individual book, so you would divide the price you paid (d) by the number of books you bought (5). Then you would multiply that answer by 7 to find out how much seven books would cost. Therefore:

(d/5) x 7

EXAMPLE:

Let's say I paid $20 for 5 books. I would need to find out how much I paid for each book, so I would divide 20 by 5 (which is, of course, 4). $4 is how much you paid per book, so therefore to find the price of seven books you would multiply seven by four, which equals 28 :)

so basically:

(20/5) x 7 = 28

I really hope I explained that well :o

EDIT: WHAT!! You eliminated the answer?? That means it wasn't correct??

Well darn it then!! It works, I can't see how its wrong! O_o

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Originally Posted by ILoveMyAbbyGirl

The answer to the first one is b=2a+11. Simply just solve for b. They give you b-3=2(a+4). Add three to both sides to get b=2a+8+3. Add together and get b=2a+11.

The second one, you could set up as a ratio. p over r (it takes p pounds to plant r rosebushes) equals x over m (x number of pounds to get m number of rosebushes). So it should look like p/r = x/m . Cross multiply (p times m and r times x) and you will get pm = rx. Divide by r and get (pm)/r.

Third: Like Jess said, divide d by five, and you will get d/5. Then multiply by 100 to get the cents. You would get 100d/5. That is the price in cents for ONE BOOK. You need SEVEN. So you will multiply by 7, and get 700d/5.

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Ah, thanks!! That makes complete sense ;)

I just submitted it and got them all right. Thank you again!!

EDIT: Thanks, Jess and boscibo for your help! :D

I was too slow, AND wrong LOL

I suck at the "easy" problems. I took too many "advanced" classes :(

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Originally Posted by Jessika

I was too slow, AND wrong LOL

I suck at the "easy" problems. I took too many "advanced" classes :(

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LOL I just looked at it and was like ... hmmm ... I'm confused again. LOL

I'm the same way. Hard problems, bring 'em on. The easy ones are really hard for me :o I love math, though, and when I went to public school I always had people running to me for the hard problems and I went to other people for the easy ones. ;)

No prob, lol. Math is my favorite subject. :)

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Originally Posted by .sarah

LOL I just looked at it and was like ... hmmm ... I'm confused again. LOL

I'm the same way. Hard problems, bring 'em on. The easy ones are really hard for me :o I love math, though, and when I went to public school I always had people running to me for the hard problems and I went to other people for the easy ones. ;)

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Well what confused me is that, my answer worked. O_o Like I even did an example LOL

But yeah, I whizzed through trig and pre-calc and even college algebra (which really isn't even that hard) but like "Easier" algebra problems I mess up anymore :(