OG详解-OG9 数学1 Q7

The correct answer is 224. It’s given that a student council group uses the function p(x) = 5x-220 to determine their profit p(x), in dollars, for selling x school posters. Substituting 900 for p(x) in the given function yields 900 = 5x-220. Adding 220 to each side of this equation yields 1,120 = 5x. Dividing each side of this equation by 5 yields 224 = x. Therefore, in order to earn a profit of $900, they must sell 224 school posters.