How much of a 60% acid solution must be mixed with 50 gallons of a 24% acid solution to obtain a solution that is 50% acid?
a.
130 gal
c.
13 gal
b.
125 gal
d.
none of these

X gallons of a 60% acid solution contains 60%×x=0.6x gallons of acid.
50 gallons of a 24% acid solution contains 24%×50=0.24×50=12 gallons of acid.

After mixing, there will be x+50 gallons of a solution, and 0.6x+12 gallons of acid. The concentration must be 50%, so the volume of acid divided by the volume of the solution is 50%, or 0.5.



The answer is A. 130 gallons.