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

Oct. $1-$ Inventory $70$ units @ $$22$

Oct$\mathrm{.}7-$Sale $57$ units

Oct. $15-$ Purchase $83$ units @ $$23$

Oct. $24-$ Sale $17$ units

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

a$.$ Cost of goods sold on October $24---$$fill in the blank $1$

b$.$ Inventory on October $31---$$fill in the blank $2$