Subject: mathqa
Question: a , b and c started a business with a total investment of rs . 72000 . a invests rs . 6000 more than b and b invests rs . 3000 less than c . if the total profit at the end of a year is rs . 8640 , find a ' s share .
Option: 
A: rs . 2880
B: rs . 3360
C: none of these
D: rs . 3240
Answer: D