Jorge is 10 and his father is 40.
If you use two-variable equations and solve, you'll find how old Jorge is, and then being able to find how old his father is.
4J - F = 0
2J - F = 20
You'd negate the bottom equation so you can have a positive F and a negative F so they cancel out. So:
4J - F = 0
-2J + F = -20
...
2J = -20, and that makes Jorge -10 years old, but because you can't be a negative age, he's just 10 years old!
And if he's 10 and his father is 40, his father is 4 times older. And in twenty years, Jorge will be 30 and his father will be 60, making his father only 2 times older.
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