The correct answer for this is 12
Just think of it....use the guess and change method to get this answer.
Think of ways to convert 15 into a fraction.
there's 5's but it's not a 1/5 fraction. (i got 1/5 from 15 reduced to 20%)
Since the number for finding 1\5 (the correct fraction) was 3 i simply added 3+3+3+3 to get 1\5 (3) to 12 (4\5)
hope you understand! :)