Question 1123277
 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)