.. good question
grocery
$ 2500*.33 ( average percent margin on grocery) =$ 825 =>>this is minimum bastards makes way more then that.
monthly 825*30 = $24750
therefore gas+ grocery = $12742 + $24750 = $ 37491 which is just revenue, not including lottery, phone card
now expenses
1) employee 18hrs* $9 average rate = $262/day
monthly 262*30 = $4860
2) rent = $7000
3) electricity + water = $ 3000
4) insurance = $ 750
5) phone + utilities = $400
6) pump repair and misc expanse = $500
7) last but not least
THEFT FROM EMPLOYEE + CROOK CUSTOMERS = $ 600 lets assume
Total Expanse = $ 17110
gross profit = $ 37491 - 17110 = $20381
according to my calculation.
Conclusion: store is doing great job.