One canned juice drink is 25? % orange? juice; another is 5? % orange juice. how many liters of each should be mixed together in order to get 20 l that is 15? % orange? juice?

Let be the amount (by volume) of the first juice drink, and the amount of the second that you will use in the mixture.

We want a mixture of 20 L, so

For each liter of the first drink, 0.25 L will be orange juice. For each liter of the second drink, 0.05 L will be orange juice. We want the new mixture to end up with 0.15 L of orange juice for every liter of the mixture, so that

Now we solve the system:

the answer is ! ?