Aria Acoustics, Inc. $($AAI$),$ projects unit sales for a new seven$-$octave voice emulation implant as follows:

Year Unit Sales

$190,000$

$2103,000$

$3117,000$

$4112,000$

$593,000$

Production of the implants will require $$1,690,000$ in net working capital to start and additional net working capital investments each year equal to $15$ percent of the projected sales increase for the following year. Total fixed costs are $$1,590,000$ per year, variable production costs are $$310$ per unit, and the units are priced at $$425$ each. The equipment needed to begin production has an installed cost of $$21,900,000.$ Because the implants are intended for professional singers, this equipment is considered industrial machinery and thus qualifies as seven$-$year MACRS property. In five years, this equipment can be sold for about $20$ percent of its acquisition cost. The tax rate is $24$ percent and the required return on the project is $18$ percent. Refer to Table $8\mathrm{.}3.$

a$.$ What is the NPV of the project? $($Do not round intermediate calculations and round your answer to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$

b$.$ What is the IRR? $($Do not round intermediate calculations and enter your answer as a percent rounded to $2$ decimal places, e$.$g$.,32\mathrm{.}16.)$

can you please specify on how to calculate the change in net working capital for each year, $($not sure how to determine the change in NWC particularly on year $5)$