2/25 = x/80....2 chaperones to 25 students = x chaperones to 80 students cross multiply because this is a proportion (25)(x) = (2)(80) 25x = 160 x = 160/25 x = 6.4......so basically, since u cant have .4 of a person, we need to round up, so the school needs 7 chaperones for 80 students