Please answer using interest factor method

Question: This question relates to a cash flow series that starts a month from now in the amount of 41 million yen, and continues for the following 23 months, with a decreasing gradient in the amount of 500,000 yen at the rate of 0.313% per month. Today is March 31. On April 1 two years from now, the interest rate changes to 0.393% per month. Another series of cash flows that starts on April 30 two years from now starts with a cash flow that is negative in the amount of 31.3 million yen. That second series of cash flows is a uniform series and consists of 36 cash flows. Find the Net Present Worth of both series