word problem

Question

Problem Page
The Hall family and the Smith family each used their sprinklers last summer. The water output rate for the Hall family's sprinkler was
40L
per hour. The water output rate for the Smith family's sprinkler was
25L
per hour. The families used their sprinklers for a combined total of
65
hours, resulting in a total water output of
2075L
. How long was each sprinkler used?

Answer 1

Let x = the number of hours the Hall sprinkler was used

Let y = the number of hours the Smith sprinkler was used

x + y = 65       x = 65 - y

40x + 25y = 2075

40(65 - y) + 25y = 2075

2600 - 40y + 25y = 2075

-15y = -525

y = 35 hours

x = 65 - 35

x = 30 hours