Grey Company has the following information regarding its merchandise transactions for $2022.$

$\backslash$table$[[$Jan$.1,$Balance,,$100$ units @ $$150($unit cost$)],[$Mar$.30,$Purchase,,$300$ units@$$155],[$Apr$.15,$Sale,$200$ units,$],[$Jun$.2,$Purchase,,$200$ units@$$145],[$Aug$.5,$Sale,$250$ units,$],[$Oct$.8,$Purchase,,$270$ units@$$63],[$Dec$.10,$Sale,$355$ units,$]]$

$($a$)$ Determine units available for sale and cost of goods available for sale.

$($b$)$ Using FIFO method, determine cost of goods sold $($CoGS$)$ and ending inventory $($$$).$