The Thompson family and the Evans family each used their sprinklers last summer. The water output rate for the Thompson family's sprinkler was 20 L per
 hour. The water output rate for the Evans family's sprinkler was 25 L per hour. The families used their sprinklers for a combined total of 55 hours, resulting in a
 total water output of 1225 L. How long was each sprinkler used?