SOLUTION: Amy is 7 years older than Tom while Tom is twice as old as Jill. Chris is 3 times as old as Amy. If the sum of Chris and Amy's age is 68. Find Toms age. Please help. i have t

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Question 509695: Amy is 7 years older than Tom while Tom is twice as old as Jill. Chris is 3 times as old as Amy. If the sum of Chris and Amy's age is 68. Find Toms age.

Please help. i have the answer but my equation is wrong...
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let a = Amy's age
Let t = Tom's age
Let j = Jill's age
Let c = Chris's age
----------------------
given:
(1) +a+=+t+%2B+7+
(2) +t+=+2j+
(3) +c+=+3a+
(4) +c+%2B+a+=+68+
--------------
There are 4 unknowns and 4 equations
so this should be solvable
Substitute (3) into (4)
(4) +c+%2B+a+=+68+
(4) +3a+%2B+a+=+68+
(4) +4a+=+68+
(4) +a+=+17+
Substitute this result into (1)
(1) +a+=+t+%2B+7+
(1) +17+=+t+%2B+7+
(1) +t+=+17+-+7+
(1) +t+=+10+
Substitute this result into (2)
(2) +t+=+2j+
(2) +10+=+2j+
(2) +j+=+5+
and, also
(3) +c+=+3a+
(3) +c+=+3%2A17+
(3) +c+=+51+
----------------
Amy's age is 17
Tom's age is 10
Jill's age is 5
Chris's age is 51