Help struggling with this for long time

Joe's Copy Center hires a new employee. Joe knows he has to be patient with the employee until the employee gains enough experience to meet production standards. Joe is unsure of the learning curve in his operation, but he knows the first job by a new employee averages 40 minutes and the second job averages 32 minutes. Assume all jobs to be equal in size.

What is the learning-curve percentage, assuming the cumulative average-time method?

What is the time for a new employee to do 32 jobs with this learning curve using the cumulative average-time method? You may use an index of -0.1520.