% variables var float: R; % quarterly repayment var float: P; % principal initially borrowed var 0.0 .. 10.0: I; % interest rate % intermediate variables var float: B1; % balance after one quarter var float: B2; % balance after two quarters var float: B3; % balance after three quarters var float: B4; % balance owing at end constraint B1 = P * (1.0 + I) - R; constraint B2 = B1 * (1.0 + I) - R; constraint B3 = B2 * (1.0 + I) - R; constraint B4 = B3 * (1.0 + I) - R; solve satisfy; output [ "Borrowing ", show_float(0, 2, P), " at ", show(I*100.0), "% interest, and repaying ", show_float(0, 2, R), "\nper quarter for 1 year leaves ", show_float(0, 2, B4), " owing\n" ];