Question

To make purple paint we need to maintain a 3:2 ratio of red paint to blue paint .Red paint cost $20 a gallon and blue paint cost $25 a gallon .A coupon gives 10% discount on red paint and 20% discount on blue paint .If you have$500 for paint .what is the maximum amount of red and blue paint you can buy to make purple paint .

Answer 1

red (w/discount) ... $18 per gallon

blue (w/discount) ... $20 per gallon

(3 n * 18) + (2 n * 20) ≤ 500

54 n + 40 n ≤ 500 ... 94 n ≤ 500 ... n ≤ 5 15/47

3 n = 15 gal red ... 2 n = 10 gal blue