How to solve this word problem: When Dad was 35 I was 7. Dad is now 3 times my age. How old are we?

The problem gives that when the father was 35, the child
was 7 and now the father's age is 3 times the child's
age.

When the child was 7, the father was 35, this puts
their age difference at 35 - 7 = 28. This does not change as the child gets
older.

If the present age of the child is C and that of the
father is F.

F = 3*C

F = C +
28

3*C = C + 28

2C =
28

C = 14

The present age of
the child is 14 and the father is 42 years old.