I need to write and solve the equation. I don't know how to solve these problems.
She needs 10 liters of 10%
amount of 5% = x amount of acid = .05x
amount of 40% = (10-x) amount of acid = .40 (10-x)
summed, these = the amount of acid in the final product = .10 (10)
.05x + .4 (10-x) = .10 (10) solve for 'x' the amount of 5% then 40% amount = 10-x