The Green family and the Adams family each used their sprinklers last summer. The water output rate for the Green family's sprinkler was 30 L per hour. The water output rate for the Adams family's sprinkler was 20 L per hour. The families used their sprinklers for a combined total of 55 hours, resulting in a total
water output of 1400 L. How long was each sprinkler used?
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?
Green family's sprinkler: [hours
Adams family's sprinkler: I hours