SOLUTION: tom's father is thrice as old as Tom.10 years ago Tom's father's age was 7 times his age. What is Tom's current age ?

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Question 1123277: tom's father is thrice as old as Tom.10 years ago Tom's father's age was 7 times his age. What is Tom's current age ?
Found 2 solutions by josmiceli, ankor@dixie-net.com:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let Tom痴 present age = +a+
Let Tom痴 father痴 present age = +b+
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(1) +b+=+3a+
(2) +b+-+10+=+7%2A%28+a+-+10+%29+
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Plug (1) into (2)
(2) +3a+-+10+=+7a+-+70+
(2) +4a+=+60+
(2) +a+=+15+
Tom is 15 now
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Check:
(1) +b+=+3%2A15+
(1) +b+=+45+
And
(2) +b+-+10+=+7%2A%28+a+-+10+%29+
(2) +b+=+7%2A5+%2B+10+
(2) +b+=+45+
OK

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
tom's father is thrice as old as Tom.
f = 3t
10 years ago Tom's father's age was 7 times his age.
f-10 = 7(t-10)
f - 10 = 7t - 70
f = 7t - 70 + 10
f = 7t - 60
replace f with 3t, from the first statement
3t = 7t - 60
3t - 7t = -60
-4t = -60
t = -60/-4
t = +15 yrs is Tom's age
:
:
Check this in the statement (f=3*15)
" 10 years ago Tom's father's age was 7 times his age. "
45 - 10 = 7(15 - 10)
35 = 7(5)