Question

Nick is now seven times as old as Harry. In 6 years, Nick will be five times as old as Harry. How old will Harry be in 6 years?

Answer 1

N=7*H
N+6=5*(H+6)

Substituting the first equation on the second:
7H+6=5H+30
7H-5H=30-6
2H=24
H=12 (This is Harry's current age)
In 6 years, Harry will be 18

Answer 2

let harrys present age = x years
then nick is 7x years
in 6 years
harrys age = x+6
nicks age = 7x + 6

ATQ 7x + 6 = 5(x+6)
=> 7x + 6 = 5x + 30
=> 7x - 5x = 30 - 6
=> 2x = 24
=> x = 24/2 = 12

so Harry's present age = 12 years
After 6 years he will be 12+6 = 18 years