The recipe for mint chocolate ice cream requires 2/4 cups of cream for 5 people. you need ice cream for 8 people. How much cream will you need?

Just set up a simple ratio equation:

x/(2/4) = 8/5
x/(1/2) = 8/5
5x = 4
x = 4/5 cups of cream

why would a recipe call for 2/4 cups instead of 1/2 cup??