If you have $82 in your bank account and you write checks for $54, $35, and $15, then the total amount you have written in checks is $54 + $35 + $15 = $104.
So the remaining balance is $82 - $104 = -$22, which means you are now overdrawn.
After you deposit $35 and $42, the new balance will be $82 - $22 + $35 + $42 = $155
So after the deposit, the account balance is $155
It is important to keep track of your bank account balance, if you do not have enough funds in the account and the check you wrote is cashed the bank will bounce the check and incur additional fees.