6% of it is rs. 2400

HERE IS THE ANSWER:
LET THE NUMBER BE M.
6% OF M = 2400 
  6   x M = 2400
100
M =   2400 x 100  
                  6
M =   240000  
               6
M = 40000 Rs.
SO, 6% OF 40000 Rs = 2400

HOPE IT HELPS!!