I dont understand how to do this :( can someone show me step by step?

The Jones Company has just completed the third year of a five$-$year MACRS recovery period for a piece of equipment it originally purchased for $$300,000.$

a$)$ What is the book value of the equipment?$$

b$)$ If Jones sells the equipment today for $$180,000$ and its tax rate is $35\%,$ what is the after$-$tax cash flow from selling it$?$

a$.$ What is the book value of the equipment?

b$.$ If Jones sells the equipment today for $$180,000$ and its tax rate is $21\%,$ what is the after$-$tax cash flow from selling it$?$

c$.$ Just before it is about to sell the equipment, Jones receives a new order. It can take the new order if it keeps the old equipment. Is there a cost to taking the order

and if so$,$ what is it$?$ Explain.

Note: Assume that the equipment is put into use in year $1$ and the new order will consume the remainder of the machine's useful life.

a$.$ What is the book value of the equipment?

The book value of the equipment after the third year is $ $($Round to the nearest dollar.$)$

b$.$ If Jones sells the equipment today for $$180,000$ and its tax rate is $21\%,$ what is the after$-$tax cash flow from selling it$?$

The total after$-$tax proceeds from the sale are $quad $($Round to the nearest dollar.$)$

c$.$ Just before it is about to sell the equipment, Jones receives a new order. It can take the new order if it keeps the old equipment. Is there a cost to taking the order

and if so$,$ what is it$?$ Explain. $($Select the best choice below.$)$

A$.$ No$,$ Jones already owns the machine, so there is no cost to using it for the order.

B$.$ Yes, the cost of taking the order is the lost $$86,400$ in book value.

C$.$ Yes, the cost of taking the order is the extra depreciation on the machine.

D$.$ Yes, the cost of taking the order is the lost after$-$tax cash flow of $$160,344$ from selling the machine.