Question does not specify, but I would assume monthly loan payments. If that is the case, monthly debt service is $299,775.26, and annual debt service is $3,597,303.15. The loan constant is equal to the annual debt service divided by the original principal balance of the loan ($50,000,000). The correct answer is 0.07195 or 7.195%. If we assume annual payments, the payment amount in the other answer is correct. To get the loan constant under this scenario, divide by $50,000,000. You should get 0.07265, or 7.265%.