Question

A pharmacist has a 12% boric acid solution and a 20% boric acid solution. How much of each must he use to make 80 grams of a 15% boric acid solution?

PLEASE HELP FAST

Answer 1

If x = the amount of 12% and y = the amount of 20%, then x + y = 80

Since we need 80 grams of 15%, 80(.15) = 12.

We are given that .12x + .20y = 12.

We can solve the first equation for x or y. Let's do x.

x = 80 - y

.12(80 - y) + .20y = 12
9.6 - .12y + .20y = 12
.08y = 2.4
y = 30

x = 80 - 30 = 50