A recipe calls for 2 cups of flour to make 24 cookies. If you want to make 36 cookies, how much flour do you need?

Solution:
Let the number of cups of flour required to make 36 cookies be x

Using the concept of proportion

2:24::x:36

Thus 2*36= x*24

On solving the above equation

x=3

Thus you need 3 cups of flour to make 36 cookies