Answer: the Russell family used their sprinkler for 40 hours.
the Gonzalez family used their sprinkler for 20 hours.
Step-by-step explanation:
Let x represent the number of hours for which the Russell family used their sprinkler.
Let y represent the number of hours for which the Gonzalez family used their sprinkler.
The families used their sprinklers for a combined total of 60 hours. It means that
x + y = 60
The water output rate for the Russell family's sprinkler was 35L per hour. The water output rate for the Gonzalez family's sprinkler was 40L per hour. The total water output of both families was 2200L. It means that
35x + 40y = 2200- - - - - - - - - - --1
Substituting x = 60 - y into equation 1, it becomes.
35(60 - y) + 40y = 2200
2100 - 35y + 40y = 2200
- 35y + 40y = 2200 - 2100
5y = 100
y = 100/5
y = 20
x = 60 - y = 60 - 20
x = 40
