Question 3708
Fahad = x
Ahmad=y
Fahad seven years ago = x-7
Ahmad seven years ago = y-7

x+y=38 OR y=38-x

Seven years ago:
(x-7)=3(y-7)
x-7=3y-21
x+14=3y

Substitute 38-x for y
x+14=3(38-x)
x+14=114-3x

add 3x-14 to both sides
4x=100
x=25

so y=13

This is correct because 7 years ago Fahad was 18  and ahmad was 6