A store purchased a Brand C computer for the same amount that is paid for a Brand D computer then sold them both at higher prices. The store's gross profit on the Brand C computer was what percent greater than its gross profit on the Brand D computer?
(1) The price at which the store sold the Brand C computer was 15% greater than the price at which the store sold the Brand D computer.
(2) The store's gross profit on the Brand D computer was $300.
intuitive solution -> E because the purchase price is not known.
formal solution: x - purchase price of computers, y - gross profit on C, z - gross profit on D.
question: what is (y-z)/x?
1: (y+x) = 1.5*(z+x)
2: z = 300
1&2: calculate (y-300)/x
x = 700 -> y = 1.5*(700+300)-700 = 800 -> (y-300)/x = 500/700
x = 200 -> y = 1.5*(200+300)-200=550 -> (y-300)/x = 250/200 = 500/400
obviously those two numbers are different -> E