Using the formula I = P• i • t where I is interest and P is principal, i is interest rate and and t is time in years I found that the principal is $2333.33
0.05x3=0.15 350/0.15=2333.33 The answer to the second questions is 32.1429% per year and the equation is r = (1/t)(A/P - 1) I hope this helps you should check my work anyway