Math word problem help

Question

a scientist has two solutions,which she has labeled solution A and solution B . Each contains salt. She knows that solution A is 40% salt and solution B is 90% salt. she wants to contain 70 ounces of mixture that is 55% salt. How many ounces of each solution should she use?

Answer 1

Hi, Tracie.

So let's call X the amount needed of A

Then, amount of solution B = 70 - X

 

So,

.40X + .90(70 - X) = .55(70)

.40X + 63  - .90X = 38.5

 

 

24.5 = .50X

 

49 = X

 

So she needs 49 ounces of Solution A

and 70 - 49 = 21 ounces of solution B