Question

How many gallons of a 80​% antifreeze solution must be mixed with 100 gallons of 25​% antifreeze to get a mixture that is 70​% ​antifreeze? Use the​ six-step method.

Answer 1

0.7X+0.25*100=0.6(100+X)
0.7X+25=60+0.6X
0.7X-0.6X=60-25
0.1X=35
X=35/0.1

X=350 GALLONS OF 70%

Answer 2

We have 100 gallons of 25% antifreeze.
How much of 80% antifreeze do we need to add to make a 70% solution?

.25 * 100 + .80x = .70 * 100 + x
25 + .80x = 70 + .7x
.1x = 45
x = 450 gallons of 80% must be added to make a 70% solution.