For maximum protection, a car radiator needs 7 parts antifreeze to 3 parts distilled water. If the radiator will hold 21 L of the mixture, how much...

Hello!

This problem is relatively simple.

If the radiator is filled with 7 (equal) parts of antifreeze and 3 parts of distilled water (these parts have the same volume as parts of antifreeze), then there are 7+3=10 equal parts. And they together make 21 L. Therefore each part has a volume of (21 L) / 10 = 2.1 L.

Now we can easily find the volume of antifreeze and water: 7*2.1 L = 14.7 L of antifreeze and 3*2.1 L = 6.3 L of water.

The answer: 14.7 L of antifreeze will be needed, 6.3 L of water will be needed.