what would be the monthly mortgage payments for each of the following situations? $($Round mor factors and final answers to $2$ decimal places. Omit the $"$$$"$ sign in your response.$)$

a$)$ A $$64,000,15-$year loan at $7\mathrm{.}0$ percent APR compounded semi$-$annually

b$)$ A $$140,000,25-$year loan at $5\mathrm{.}5$ percent APR compounded semi$-$annually

c$)$ A $$104,000,20-$year loan at $4\mathrm{.}0$ percent APR compounded semi$-$annually