The Sanders family and the Aoki family each used their sprinklers last summer. The water output rate for the Sanders family's sprinkler was 30
L
per hour. The water output rate for the Aoki family's sprinkler was
25
L
per hour. The families used their sprinklers for a combined total of
40
hours, resulting in a total water output of
1075
L
. How long was each sprinkler used?