Question

How many gallons of a 34% pure acid solution must be mixed with 30 gallons of a 90% solution to get a 55% solution?

Answer 1

By multiplying the num of gallons by the percent of acid, you get gallons of pure acid
set up equation equating pure acid content

--> 30(.9) + x(.34) = (x+30)(.55)

--> 27 + .34x = .55x + 16.5

solve for x