Answer:the number of hours that the Simmons family used their sprinklers last summer is 30
the number of hours that the Wright family used their sprinklers last summer is 25
Explanation:
Let x represent the number of hours that the Simmons family used their sprinklers last summer.
Let y represent the number of hours that the Wright family used their sprinklers last summer.
The families used their sprinklers for a combined total of 55 hours, it means that
x + y = 55
The water output rate for the Simmons family's sprinkler was 20l per hour. The water output rate for the Wright family's sprinkler was 35l per hour. The total water output was 1475l. It means that
20x + 35y = 1475 - - - - - - - - - - 1
Substituting x = 55 - y into equation 1, it becomes
20(55 - y) + 35y = 1475
1100 - 20y + 35y = 1475
- 20y + 35y = 1475 - 1100
15y = 375
y = 375/15 = 25
x = 55 - y = 55 - 25
x = 30