How do I calculate the interest expense I cant seem to figure that part out for anything

Required information Franklin borrows funds, in increments of $1.000, and repays them on the last day of the month. Repayments may be made in any amount available. The company also pays it vendors on the last day of the month. It pays Interest of 1 percent per month in cash on the last day of the month. To be prudent, the company desires to maintain a $18.000 cash cushion. Prepare a cash budget. (Any repayments/shortage which should be indicated with a minus sign.) Show less Cash Budget October November December $ 0 72.000 72.000 104.400 194,400 233.280 233.280 Section 1: Cash Receipts Beginning cash balance Add: Cash receipts Total Cash available Section 2: Cash Payments For inventory purchases For selling and administrative expenses Interest expense Purchase of store fuctures 84,672 20.400 0 128,822 30.320 140.450 41.624 101.000 0 0 305.872 168,142 188,080 (233.872) 20.258 45.200 Total budgeted disbursements Section 3: Financing Activities Surplus (shortage) Borrowing repayment) Ending cash balance 233.672) 5 5 20.258 $ 45200