The first time you look at this, you would think that you can just cancel the (m+2) off of each side. But then you're left with (m+3) = (m-2), and there's no solution for this. So you have to go back and do it the hard way.
Expand each side of the equation. (Clear the parentheses.)
Let, Harry's age - x then Nick is 7x. After 6 years, Harry is x+6 and Nick is 7x+6 So, 7x+6= 5(x+6)=> 2x = 30-6X = 12 In 6 years, Harry will be 12+6 = 18 years (Ans)