Question 157305
.7x+.1*18=.25(x+18)
.7x+1.8=.25x+4.5
.7x-.25x=4.5-1.8
.45x=2.7
x=2.7/.45
x=6 gallons of 70% acid is needed.
Proof:
.7*6+.1*18=.25(6+18)
4.2+1.8=.25*24
6=6