Algebra 1 honors
posted by Lisa .
A pineapple drink contains 15% pineapple juice. How much pure pineapple juice should be added to 8 quarts of the drink to obtain a mixture containing 50% pineapple juice.

.15*8+X=.5(8+X)
1.2+X=4+.5X
X.5X=41.2
.5X=2.8
X=2.8/.5
X=5.6 QTS. OF PURE PINEAPPLE JUICE IS USED.
PROOF:
.15*8+5.6=.5(8+5.6)
1.2+5.6=.5*13.6
6.8=6.8 
How many quarts of pure pineapple juice should Theo add to a 20% pineapple drink to create 5 quarts of 50% of pineapple juice mixture?