please help me with part b) show working so i can understand how to do it and put answer in % to 1d.p thank you

An integrated, combined cycle power plant produces 300 MW of electricity by gasifying coal. The capital investment for the plant is $630 million, spread evenly over two years. The operating life of the plant is expected to be 18 years. Additionally, the plant will operate at full capacity 72% of the time (downtime is 28% of any given year). The MARR is 8% per year. a. If this plant will make a profit of three cents per kilowatt-hour of electricity sold to the power grid, what is the simple payback period of the plant? Is it a low-risk venture? b. What is the IRR for the plant? Is it profitable? a. The simple payback period of the plant is 11.1 years. (Round up to one decimal place.) It's a high-risk venture. b. The IRR for the plant is %. (Round to one decimal place.)