One fruit punch has 10% fruit juice and another is 90% fruit juice. How much of the 10% punch should be mixed with 30gal of the 90% punch to create fruit punch that is 25% fruit juice?

Answer 1

.9(30)+.1x = .25(30+x)

9(30) + x = 2.5(30+x)

270 + x = 75 +2.5x

1.5x = 195

x =195/1.5 = 130 gallons of 10%

or

25-10 =15

90-25 = 65

65/15 = 13/3 = 4 1/3 times as much 10% as 90%

30 times 4 1/3 = 130 gallons