A 20% acid solution is mixed with a 70% acid solution to get 50 liters of a 40% solution.

How much of the 70% solution is used?

A.) 20 liters

B.) 25 liters

C.) 30 liters

20% solution+70% solution=50% solution

total is 50

so the quantaties are x and 50-x (x+50-x=50)

0.2 (50-x) + 0.7 (x) = 0.4 (50)

solve

distribute

10-0.2x+0.7x=20

10+0.5x=20

minus 10 both sides

0.5x=10

times 2

x=20

A is answer