Question

How much pure water must be mixed with 10 liters of a 25% acid solution to reduce it to a 10% acid solution?

Answer 1

Liters Equation:
x + 10 = y

Water Equation:
1x + .75(10) = .90y

x = x
y - 10 = .90y - 7.5
y - .90y = 10 - 7.5
.10y = 2.5
y= 2.5/.10
y = 25
x = 15

Therefore `15 liters` of pure water was added, which produced a total of 25 liters of a 10% solution.