Question

A recipe for rice pudding calls for 2 1/2 cups of milk. The recipe makes 5 servings. How many cups of milk are needed to make 8 servings?

Answer 1

8/5 as many servings, so 8/5 as much milk

8/5 * 5/2 = 8/2 = 4 cups

or, note that 2 1/2 = 5/2 cups for 5 servings is 1/2 cup per serving
8 * 1/2 = 4

Or, if they want you to use a proportion, then
x/8 = (5/2) / 5

Answer 2

2 1/2 divided by 5 = 5/2 x 1/5 =5/10=1/2x8=4 cups

Answer 3

4