Here are the possible expenses that you might encounter during your tenure here in Qatar:

Grocery. > QAR 3,500
Infant Milk > QAR 500
Normal resto 250x10 > QAR 2,500
School bus per sem > QAR 1,500
Car Installment > QAR 2,000
Miscellaneous > QAR 1,000
=========
QAR 11,000

If you have a gross monthly salary with an amount of 24 k - 11,000, you stillhave QAR 13,000 savings every month. The prices above may be vary from one restaurant, grocery store and school to another (+ some unexpected expenses like shopping). I hope that the above probable costs might help you decide about your offer.