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?

You have 2 different perfumes at 2 different prices that you have to mix to get a total of 3 ounces of a new perfume. A's amount of perfume needed is x, so B's amount of perfume needed is 3-x (cuz you can only have a total of 3 ounces). The amount A costs per ounce is 15 and the amount that B costs per ounce is 35. So multiply each amount by what it costs, add those together and set them equal to 63 (cuz your equation is based on money). 15x + 35(3 - x) = 63. Distribute the 35 into the parenthesis to get 15x + 105 - 35x = 63. Combine the x terms and move the 105 and solve for x to get that x = 2.1 ounces. You need 2.1 ounces of A and 1.5 ounces of B to get what you want.