There are two orange and pineapple juice cocktails. The first contains 40% orange juice and the second 80%.

There are two orange and pineapple juice cocktails. The first contains 40% orange juice and the second 80%. The cocktails are mixed and the result is 20 liters of a cocktail containing 70% orange juice. What is the volume of each cocktail?

According to the condition of the problem, the resulting 20 liters of cocktail contains 70% orange juice, that is, its volume is:

20 * 70: 100 = 14 liters.

Let’s say that the quantity of the second cocktail was x liters, then the quantity of the first cocktail was 20 liters.

Thus, we can, according to the condition of the problem, compose the following equation:

0.4 * (20 – x) + 0.8 * x = 14,

8 – 0.4 * x + 0.8 * x = 14,

0.4 * x = 14 – 8,

x = 6: 0.4

x = 15 (l) – the volume of the second cocktail.

20 – 15 = 5 (l) – the volume of the first cocktail.

Answer: 5 liters and 15 liters.