Question 734532
100*.18=.20x+.12(100-x)
18=.20x+12-.12x
.20x-.12x=18-12
.08x=6
x=6/.08
x=75 gallons of 20% acid is used.
100-75=25 gallons of 12% acid is used.
proof:
100*18=.20*75+.12*25
18=15+3
18=18