At the beginning of this month, the balance of mark's checking account was $275.35. so far this month, he has received a paycheck via direct deposit of $987.25, was charged a monthly service fee by his bank of $15.00, used a debit card linked to his account to make a purchase of $43.22, wrote a check for $57.26 that has already been deposited, and deposited a check for $100.00. what is the current balance of mark's checking account?