The loan principal is 20,000 yuan, the loan term is one year, and the annual interest rate is 5%. According to the interest calculation formula: interest = principal × interest rate × years, it can be calculated that the loan interest is: interest = 20,000 yuan ×5%× 1 year = 1 10,000 yuan, and the interest to be paid by the rural credit bank when it borrows 20,000 yuan is 1 10,000 yuan.