Hello, rainbowx!

How much water should be added to 30 gallons of a solution that is 70% antifreeze

in order to get a mixture that is 60% antifreeze?

Since water is added to the solution, we must think in terms of.water

The original solution is 30 gallons which is 30% water.

. . It contains: gallons of water.

Then gallons of water is added.

The final mixture contains: gallons of water. .[1]

But we know that the final mixture will be gallons which is 40% water.

. . It contains: gallons of water. .[2]

We just described the final amount of waterin two ways.

There is our equation! . . .

Got it?