## Algebra: A Combined Approach (4th Edition)

number of gallons × acid strength = amount of acid x=# of gallons Gallons of pure acid = x Gallons of 40% acid = 2 Gallons of 70% acid needed = x + 2 $1x+0.40(2)=0.70(x+2)$ $1x+0.80=0.70x + 1.40$ $1x-0.70x = 1.40-0.80$ $0.30x=0.60$ $x=0.60\div0.30$ $x=2$