Question 761900
With 100 stores, the total sales S = {{{25000*100=2500000}}} dollars per store per week

For 0 additional stores, the total sales is as given above.

For one additional store, sales will decrease by $650

So for N additional stores it will decrease by {{{650*N}}} from the initial value given above

So the equation is {{{S = 2500000 - 650*N}}}

:)