SOLUTION: Bob's age is 40% of his fathers age. Ten years from now, Bob's age will be 50% of his fathers age. How old are Bob and his father now?

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Question 1152522: Bob's age is 40% of his fathers age. Ten years from now, Bob's age will be 50% of his fathers age. How old are Bob and his father now?
Found 2 solutions by rothauserc, greenestamps:
Answer by rothauserc(4718) (Show Source):
You can put this solution on YOUR website!
Let x be Bob's age and y be his father's age, then
:
(1) x = 0.40y
:
(2) x +10 = 0.50(y +10)
:
substitute for x in equation 2
:
0.40y +10 = (y/2) +5
:
0.80y +20 = y +10
:
0.20y = 10
:
y = 50
:
x = 0.40 * 50 = 20
:
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Bob is 20 years old and his father is 50 years old
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:

Answer by greenestamps(13203) (Show Source):
You can put this solution on YOUR website!

The solution by the other tutor is fine; and of course there are many other ways to solve the problem.

I always prefer to set a problem up using only one variable if possible; so here is what I would do.

40% = 2/5, so

let 2x = son's age
let 5x = father's age

The son's age in 10 years will be half his father's age then:

The son's age is 2x=20; the father's age is 5x=50