Sapphire Inc. manufactures and sells shirts. It has two departments: Stitching and Finishing. The Stitching department has opening inventory of $500$ shirts comprised of direct materials of $$7,500$ and conversion costs of $$2,500.$ The units are estimated to be $60\%$ complete with respect to conversion costs. During the month of December, $4,500$ units were started and $3,000$ shirts were completed and transferred to the Finishing department. The ending inventory is $75\%$ complete with respect to conversion costs. The following costs were incurred during the month:

Direct materials

$$67,500$

Conversion costs

$46,250$

Total costs

$$113,750$

The company has two cost classifications$$direct materials and conversion costs. What is the total cost assigned to shirts completed and transferred out by the Stitching department? Assume direct materials are introduced at the beginning of the process. $($Round to whole dollars$)$

The answer is $77490,$ i just want to know the steps to get that answer.