Shinto is serving pizza. He serves 1/5 of the pizza to one friend and 5/12 to another friend. If he had 9/10 of a pizza to start with, how much does he have leftover.

17/60

Step-by-step explanation:

Change all of the fractions to have a common denominator:

LCM of 10, 12, 15 is 60

You get 12/60, 25/60, and 54/60.

54/60 is what he had at the start, and so you can just subtract what he gave away

54/60-12/60=42/60

42/60-25/60=17/60

17 is a prime number so you cannot simplify the fraction

17/60

Step-by-step explanation:

First we find the LCM of 10, 12, and 5, which is 60.

He started with 54/60.

He gave away 12/60, leaving 42/60.

He gave away another 25/60, leaving 17/60.

He had 17/60 of a pizza left over.