need help solving

Question

How much of a perfume that sells for $15 per ounce should be mixed with a perfume that sells for $35 per ounce to make a 3-oz bottle of perfume that can be sold for $63?

Answer 1

Let a = number of oz of the $15 perfume and b = the number of oz of the $35 perfume.

Then , a15 + b 35 = 63

a + b = 3

Solving for a & b, we find that a = 2.1 & b = .9

Check: 2.1($15) + .9($35) = $31.5 + $31.5 = $63

2.1 + .9 = 3