Perpetual inventory using FIFOBeginning inventory, purchases, and sales for Item Zeta$9$ are as follows:DateLine Item DescriptionValueOct. $1$Inventory$48$ units @ $$21$Oct. $7$Sale$37$ unitsOct. $15$Purchase$29$ units @ $$23$Oct. $24$Sale$20$ unitsAssuming 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 $31.$