A material processing oven has a first cost of $\$ 16,999$ with a life of 10 years and a salvage value of $\$ 2,500$. The corporate MARR is $12 \%$. If the system provides about $\$ 2,750$ annually, what is the PW of the project if the system is replaced by an identical system at the end of 10 years and then again at the end of 20 years?