Kristin ate 1/3 of a large sandwich. Her friend Leah ate 2/5 of the sandwich. What fraction of the sandwich did they eat in all

Answer: 11/15

you need to find the smallest common multiple, which is 15

to get a denominator of 15 for 1/3, you need to multiply 1/3 by 5, and you get 5/15

then, to get a denominator of 15 for 2/5, you need to multiply the fraction by 3 and you get 6/15 and then you add

5/15 + 6/15 = 11/15