An advertisement for an orange drink claims that the drink contain 10% orange juice. How much pure orange juice would have to be added to the drink to obtain 5 quart a mixture containing 40% orange juice?
5 quarts of 40% = 5 x .4 = 2 quarts of pure orange juice
Pure orange juice is 100% x is amount needed 5-x is the amount of 10% drink mix
1 (x) + .1 (5-x) = 2
x + .5 - .1x = 2
.9x =1.5
x = 1.5/.9 = 1 2/3 quart of pure orange needed