The Ramirez family and the Stewart family each used their sprinklers last summer. The water output rate for the Ramirez family's sprinkler was 40 L per hour.
The water output rate for the Stewart family's sprinkler was 15 L per hour. The families used their sprinklers for a combined total of 55 hours, resulting in a total
water output of 1575 L. How long was each sprinkler used?