SOLUTION: jim is now three times as old as amy. four years ago, jim was seven times as old as amy was then. Find their present ages.

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Question 549169: jim is now three times as old as amy. four years ago, jim was seven times as old as amy was then. Find their present ages.
Answer by oberobic(2304) About Me  (Show Source):
You can put this solution on YOUR website!
J = Jim's age
A = Amy's age
.
Jim is 3 times as old as Amy.
J = 3*A
.
Four years ago:
J-4 = Jim's age
A-4 = Amy's age
.
Four years ago, Jim was 7 times as old as Amy.
J-4 = 7*(A-4)
.
Substitute J=3*A
.
3A-4 = 7A - 28
.
3A -7A = -28 + 4
.
-4A = -24
.
A = 6
.
J = 3*A = 3*6 = 18
.
Check how old they were 4 years ago.
A = 6-4 = 2
J = 18-4 = 14
14 = 7*2 ?
Correct.
.
Answer: Amy is 6, and Jim is 18.
.
Done.