Given data:
initial balance in the account :$4200
Each month to be paid for rent =$600
Amount of Balalnce left in the account after paying m months rent =$1200
subract the inital amount from the balance amount.
4200-1200=3000
Thus, the amount paid for the rent is 600 then
Therefore it takes 5 months of paying rent from the account to have $1200 left.