Please include the formulas

Foot Loose, Inc., needs to purchase a new shoelace-making machine. Machines Ready has agreed to sell Foot Loose the machine for $22,000 down and four payments of $5,700 to be paid in semiannual installments for the next two years. Do-It-Yourself Machines has offered to sell Foot Loose a comparable machine for $10,000 down and four semiannual payments of $9,000 . If the current interest rate is 16% , compounded semiannually, which machine should Foot Loose purchase?