$1)$ A typewriter was purchased for $$300$ with an estimated life of $5$ years. What is the book value at the end of the third year?

$2)$ A delivery truck costs $$3000.$ Its book value at the end of the third year was $$2100.$ What amount of depreciation each year?

$3)$ If the purchases for the month were $$500,$ the beginning inventory was $$1,500,$ the ending inventory was $$1000,$ and gross profit was $$2000$ what were the sales?

$4)$ what is the amount necessary to pay a $$300$ invoice, terms $3/10,2/20,$ n$/30$ twelve days after date?

$5)$ If equipment costing $$1500,$ with an estimated life of $10$ years, was purchased, what is the annual rate of depreciation?