Perpetual inventory using LIFO

Beginning inventory, purchases, and sales for Item $88-$HX are as follows:

July $1$ Inventory $80$ units @ $$17$

July $8$ Sale $64$ units

July $15$ Purchase $89$ units @ $$20$

July $27$ Sale $75$ units

Assuming a perpetual inventory system and using the last$-$in$,$ first$-$out $($LIFO$)$ method, determine $($a$)$ the cost of goods sold on July $27$ and

$($b$)$ the inventory on July $31.$

a$.$ Cost of goods sold on July $27$

b$.$ Inventory on July $31$