Part A: Let the September price be x, then 1.2x = 1.5 x = 1.5/1.2 = 1.25 Therefore, September price is $1.25
Part B: In September, they earned 0.4 * 1.25 * 900 = $450 In October, they earned 0.4 * 1.5 * 700 = $420 Therefore, they earned more money in September.