In order to purchase a truck Shandex Transport $($ST$)$ obtained a $$50000$ loan for $5$ years at $7\mathrm{.}8\%$ compounded semi$-$annually. The loan is structured to reduce the balance owing to $$10000$ at the end of the $5$ year period. How much are ST$\text{'}$s payments at the end of each month? a$$1006\mathrm{.}08$ b$$804\mathrm{.}87$ c$$868\mathrm{.}84$ d$$834\mathrm{.}79$ e$$1070\mathrm{.}11$B