SOLUTION: Jerry is four times as old as Laura. In 20 years he will be twice as old as Laura. How old are Jerry and Laura?

Question 1050002: Jerry is four times as old as Laura. In 20 years he will be twice as old as Laura. How old are Jerry and Laura?
Answer by ikleyn(52781) (Show Source): You can put this solution on YOUR website!
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Jerry is four times as old as Laura. In 20 years he will be twice as old as Laura. How old are Jerry and Laura?
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J = 4L.           (1)

In 20 years:

J+20 = 2(L+20).   (2)

Substitute (1) into (2). You ill get

4L + 20 = 2(L+20),  or

4L + 20 = 2L + 40,

4L - 2L = 40 - 20,

2L = 20  --->  L = 10.  Laura is 10 years now.

J = 4L = 4*10 = 40.  Jerry is 40 years now.

Answer. Laura is 10 years now.  Jerry is 40 years now.

Please check it yourself.

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