one canned juice drink is 30% orange juice; another is 10% orange juice. How many liters of each should be mixed together in order to get 20L that is 15% orange juice?

Answer 1

if x is 30% then the rest (20-x) is 10%. So,

.30x + .10(20-x) = .15(20)
x = 5

So, 5L of 30% and 15L of 10%

Note how 15% is 3/4 of the way from 30% to 10%, so 3/4 of the mix is the 10% kind.