algebraic question

Question

You need a 25% alcohol solution. On hand, you have a 175 mL of a 5% alcohol mixture. You also have 60% alcohol mixture. How much of the 60% mixture will you need to add to obtain the desired solution?

Answer 1

175(.05) + .6x = (175+x).25

.6x -.25x = (175)(.25-.05)

.35x = 175(.2) = 35

x = 35/.35 = 100 mL of 60% needed to obtain a 25% mixture