$5.$ An investment requires $17,000$ today, and produces the first cash flow of $1200$ in three years $($year $3).$ Cash flow is expected to grow at $5\%$ a year after year $3$ until eternity.

a$)$What is the NPV of this investment if the discount rate is $8\%?$

NPV $=$

b$)$ What is the rate of return of this investment?

Rate of return $=$

How to calculate this in excel would be great!