The Lewis family and the Pham family each used their sprinklers last summer. The water output rate for the Lewis family's sprinkler was 30 L per hour. The water output rate for the Pham family's s
prinkler was 25 L per hour. The families used their sprinklers for a combined total of 55 hours, resulting in a total water output of 1475 L . How long was each sprinkler used?