Question 1209708
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x = average water usage, in liters, for months other than May June and July.


Over the course of those 12-3 = 9 months, x liters per month are used.
So 9x is the amount used over those months.


3*4500 = the amount of water used over May June and July combined.


9x+3*4500 = total amount of water used over the 12 months


(9x+3*4500)/12 = average water usage per month
(9x+3*4500)/12 = 4000
9x+3*4500 = 4000*12
9x = 4000*12-3*4500
9x = 34500
x = 34500/9
x = 11500/3
x = 3833.333333...
The 3's go on forever in that decimal value.


The months other than May June July should use on average roughly 3833.333 liters of water per month. 
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