The thompson family and the hill family each used their sprinklers last summer. the water output rate for the thompson family's sprinkler was 20l per hour. the water output rate for the hill family's sprinkler was 40l per hour. the families used their sprinklers for a combined total of 75 hours, resulting in a total water output of 2200l. how long was each sprinkler used?

Let T the number of hours the Thompson family used their sprinkler

Let H the number of hours the Hill family used their sprinkler

T + H = 75

H=75-T

To compute for the number of hours each family used with a combined water output of 2200, we use the following equation:

T (20) + H (40) = 2200

20T + (75-T) (40) = 2200

20T+3000-40T=2200

-20T=2200-3000

-20T=-800

T=40

H=75-40

H=35

To check:

Total water output = 40 (20) + 35 (40)

=800+1400

=2200