Question

A chemist needs to make 1000 mL of a 30% alcohol solution by mixing 25% and 55% solutions. How much of each should she use?

Answer 1

Let the amount of 25% solution be x
Let the amount of 55% solution be y

To make 1000 ml, you have
x + y = 1000

Now look at how much alcohol you have
0.25x + 0.55y = 0.3(1000)

Solve these two equations simultaneously for x and y.

Answer 2

would you plug in 1000-x for y in the second equation?

Answer 3

nevermind i got it! thank you!