Question

A laboratory has 60 cubic centimeters of a solution that is 40% HCI acid. How many cc of a 15% solution of HCI acid should be mixed with the 60 cc of 40% acid to obtain a solution of 25% HCI? How much of the 25% solution is there?

I don't know how to write this equation

First I thought (x+.15).25 = 60(.40)
but I got the wrong answer.

The answer is supposed to be 90 cc

Answer 1

If we denote V=volume of 15%HCl, then
60*0.40 + V*0.15 = (60+V)*0.25
Solve for V.

Post your answer for a check if you wish.

Answer 2

90cc