Pre-Algebra · Superchallenge problem

Every month Noah deposits $\$45$ into a savings account that starts with $\$120$. He wants to buy a bike that costs $\$900$, but a one-time $\$40$ fee is subtracted from the account at the very end, right before he withdraws the money. What is the fewest number of whole months he must save so that, even after the fee, the account has enough to buy the bike?