Algebra equations

Question

The Royal Fruit Company produces two types of fruit drinks. The first type is 35% pure fruit juice, and the second type is 85% pure fruit juice. The company is attempting to produce a fruit drink that contains 70% pure fruit juice. How many pints of each of the two existing types of drink must be used to make 120 pints of a mixture that is 70% pure fruit juice?

Answer 1

Let j = the total amount of 35% fruit juice.

Since j + the amount of 85% fruit juice will total 120 pints, the amount of 85% juice is 120 - j.

0.35j + 0.85(120 - j) = 0.7(120)

0.35j + 102 - 0.85j = 84

-0.5j = 18

j = 36 pints of 35% juice

120 - 36 = 84 pints of 85% juice