Question 48081
3/8 cup of sugar and the cookies require 3/5 cup of sugar. Sarah has 15/16 cups of sugar.

3/8 +3/5 = (15+24)/40= 39/40

15/16R39/40

Which is greater? 15/16 or 39/40
Crossmultiply to get:
15*39R16*40
585R640
As you see 585<640
Therefore 15/16 is less that 39/40
Sarah does not have enough sugar.

How much more does she need?
39/40-15/16
=78/80- 75/80
= 3/80 of a cup of sugar

Cheers,
Stan H.