On December $3,$ Windsor Company sold $$417,000$ of merchandise to Sharif Co$.,$ terms $\frac{2}{10},\frac{n}{30},$ FOB shipping point. The cost of the merchandise sold was $$257,000.$

On December $8,$ Sharif Co$.$ was granted an allowance of $$20,700$ for merchandise purchased on December $3.$

On December $13,$ Windsor Company received the balance due from Sharif Co$.$

$($a$)$