$\frac{C}{Y}=$

A husband and wife are looking into buying a new townhouse in the downtown area of a major city. The price of home they are looking at is listed at $$799,000.$ How much interest would this family pay in the first month if they purchase and then mortgage the home for $$699,000,$ if the annual interest rate is $3\mathrm{.}5\%$ compounded monthly?