For four years, Mary Thomas invested $4,080 each year in America Bank stock. The stock was selling for $56 in 2018 , for $52 in 2019 for $53 in 2020 , and for $45 in 2021. a. What is Mary's total investment in America Bank? b. After four years, how many shares does Mary own? Note: Round your intermediate calculations to 1 decimal place. Round up your final answer to the nearest whole unit. c. What is the average cost per share of Mary's investment? Note: Round up your intermediate value of "Total shares" to the nearest whole unit. Round your final answer to 2 decimal places