This is similar to Problem 9 from your Section 3.2 worksheet.

Your car radiator can hold $20$ liters of fluid. Many automotive stores sell jugs of pure antifreeze, but some also sell jugs of antifreeze that have been premixed with water. Suppose you buy a jug of $50$% antifreeze mixture as well as a jug of pure antifreeze. How many liters of each jug must you use to make enough of a $77.5$% mixture to fill your radiator?

You need of the $50$% antifreeze and of the pure antifreeze. Be sure to include units.