We do concentration=amount times percent total concentration=concentration8+concenctration20
so 12 times 8%+x times 20%=16% times (12+x)
x=amount of 20% acis solution
12*0.08+0.2*x=0.16*(12+x) solve distribute and simplify 0.96+0.2x=1.92+0.16x minus 0.96 from both sides 0.20x=0.96+0.16x minus 0.16x from both sides 0.04x=0.96 divide both sides by 0.04 x=24