The directions for a powdered drink mix say to mix the powder with water in a ratio of 2 scoops to 8 ounces. How many scoops must be used for 20 ounces of water?
Use the proportion: scoops/ounces = scoops/ounces
---> x/20 = 2/8
cross-multiply: 8x = 40
and divide: x = 5 scoops
