Question

Suppose a lab needs to make 400 liters of a 39% acid solution, but the only solutions available to the lab are 20% acid and 50% acid. What system of equations can be used to find the number of liters of each solution that should be mixed to make the 39% solution? Let c represent the number of liters of 20% acid solution and let d represent the number of liters of 50% acid solution.

Answer 1

Well you are given that the amount in liters of the 50% solution + the amount in liters of the 20% solution is equal to 400 liters.

So the first equation is c+d=400

Answer 2

You know that the amount of acid you need in the 400 liter container is .39*400.

You know that the amount of acid in in the 20% solution is .2c and the amount of acid in the 50% solution is .5d.

So if you add the amount of acid in the 20% solution to the amount of acid in the 50% solution it is equal to the amount of acid in the 39% solution.

So the second equation is:

.2c+.5d=.39*400

Answer 3

@marshallinwashington Thanks Alot!!