A football stadium holds 17,700 seats. The lower level has 300 seats less than 4 times the number of seats in the upper level. The middle level has 500 more seats than twice the number of seats in the upper level. Let x represent the seats in the upper level. Which equation can be used to find the number of seats in the upper level? 7 x + 200 = 17,700 6 x + 200 = 17,700 7 x minus 200 = 17,700 6 x minus 200 = 17,700