Answer:
Let's denote your original balance (at the beginning of the month) is x.
After depositing twice (24.61$ and 16.49$), you got 73.31$ as the amount of total money in your account.
=> x + 24.61 + 16.49 = 73.31
=> x = 73.31 - 24.61 - 15.49
=> x = 33.21$