Answer
The Williams family used their sprinkler for 40 hours.
The Robinson family used their sprinklers for 35 hours.
Explanation
Let the number of hours that the Williams family used their sprinklers be x hours
Let the number of hours that the Robinson family used their sprinklers be y hours
They both use their sprinklers for a combined total of 75 hours
x + y = 75 (equation 1)
And this resulted in a combined total water output of 2225 L
If the Williams used their 25 L per hour sprinkler for x hours,
Total water output for the Williams family = (25) (x) = (25x) L
If the Robinson used their 35 L per hour sprinkler for y hours,
Total water output for the Robinson family = (35) (y) = (35y) L
But, their combined total water output is 2225 L
25x + 35y = 2225 (equation 2)
x + y = 75
25x + 35y = 2225
On solving this simultaneous equation, we obtain that
x = 40 hours
y = 35 hours
Hope this Helps!!!
