Question

A recipe calls for 1/2 cup of ingredient A for every 1 2/5 cups of ingredient B. You use 4 cups of ingredient A. How many cups of ingredient B do you need?

Answer 1

Let x = number of cups of ingredient B if 2 cups of ingredient A are used. Set up a proportion:  (1/2)/(1 2/5) = (2)/x. Cross multiplying we get (1/2)x = (1 2/5)(2) 
 (1/2)x = 14/5, so x = 28/5 = 5 3/5 cups.

Answer 2

You use 1 2/5 of B for every 1/2 A and they use 4 of A so times 1 2/5 by 8 and you get 11.2 cups of B