Question 44769
(amount of acid / total solution) x 100 = percent acid
(.2x + .05*80) / (x + 80) = .12
.12x + 9.6 = .2x + 4
.08x = 9.6 - 4
x = 5.6 / .08
x = 70 ml of 20% solution
check
(.20*70 + .05*80) / (70 + 80) = .12
(14 + 4) / 150 = .12
18/150 = .12
OK