(simple interest) solve each problems and explain the formula that you used and explain step by step how it is solved

Solve the following Climple interest Joine borcem 20,000 from her Quot and acros to pay him 22,000 in 15 months what Interest rate was she paying 2 2. If $4000 is borrowed at an annual interest rate of 16% . for 0.75 years that is the value of the investment after 0.75 years 3. Jam is inresting an amount at 13% simple interest for years. If he intends to have $48,200 at the end of the term what must be his principal