Answer:
Dave must mix 3/5 cups of fruit for a single cup of nuts.
Explanation:
Dave is helping his grandmother make trail mix. His grandmother asks him to add 1/5 cup of fruit for every1/3 cup of nuts.
First we find how many 1/3 cups of nuts make a single cup of nuts
1/3 + 1/3 + 1/3 = 3/3 = 1
So three 1/3 cups make a single cup of nuts
To find cup of fruit for sing cup of nuts
we multiply 1/5 by 3

Dave must mix 3/5 cups of fruit for a single cup of nuts.