Perpetual Inventory Using FIFO

Beginning inventory, purchases, and sales for Item Zeta$9$ are as follows:

Oct. $1$ Inventory $78$ units @ $$23$

$7$ Sale $55$ units

$15$ Purchase $87$ units @ $$27$

$24$ Sale $31$ units

Assuming a perpetual inventory system and using the first$-$in$,$ first$-$out $($FIFO$)$ method, determine $($a$)$ the cost of the goods sold on October $24$ and $($b$)$ the inventory value on October $31.$

a$.$ Cost of the goods sold on October $24$

b$.$ Inventory value on October $31$