Let E be the total amount earned in dollars, and let t be the number of hours worked: E = 7.5 * t The above equation can be rearranged to find the number of hours worked, given the total amount earned: t = E/7.5 Plugging the value of $33.75 into the last equation we get: t = 33.75/7.5 t = 4.5 hours The answer is: 4.5 hours.