can you show how to solve these without excell?

1. What is the payback period in years (rounded to the next whole year) of a project that requires an investment of $75,000 today and promises an annual net cash flow of $16,000 to perpetuity, starting in one year? A) 2 years B) 3 years C) 4 years D) 5 years E) 6 years 2. What is the discounted payback period for the following project? Assume a discount rate of 11%. 4 Year Cash Flow 0 1 -$20 $5 2 $9 3 S4 5 $4 $8 6 $4 7 $7 8 $9