The installment interest rate is 0. 166, the loan is 250,000 yuan a year, and the principal and interest should be repaid 22 122.93 yuan per month. If the installment interest rate is 0. 166, the loan amount is 250,000, and the term is one year, then the monthly repayable principal and interest can be calculated according to the following formula: monthly repayable principal and interest = (loan amount × monthly interest rate ×( 1+ monthly interest rate) repayment months) ÷ (1+monthly interest rate).