For four years, Marty Campbell invested $4,500 each year in Harley-Davidson. The stock was selling for $80 in 2017. $68 in 2018. $54 in 2019, and $68 in 2020. a. What is Marty's total investment in Harley-Davidson? Total investment b. After four years, how many shares does Marty own? (Round your intermediate calculations and final answer to nearest whole number.) Number of shares c. What is the average cost per share of Marty's investment? (Use the rounded number of shares computed in part b. Round your answer to 2 decimal places.) Average cost per share