How much water should be added to 8 quarts of 90% antifreeze to get a 30% solution?

16 quarts

Step-by-step explanation:

Let's say x is the volume of water.

Initially, the amount of antifreeze is the concentration times the volume: 0.90 (8).

After the water is added, the amount of antifreeze is the new concentration times the new volume: 0.30 (8 + x).

Since the amount of antifreeze doesn't change, we can set these equal and solve for x.

0.90 (8) = 0.30 (8 + x)

7.2 = 2.4 + 0.30 x

4.8 = 0.30 x

x = 16

16 quarts of water should be added.