Answer :
It's 2/5 because they both are divisible by 3 and when you divide by three on both numerator and denominator you get 2/5.
You have to divide the numerator and the denominator to reduce fractions.
You have to divide the numerator and the denominator by the same number.
6 divided by 3 = 2
15 divided by 3 =5
Answer 2/5
