cost of 1 share = 31.96
cost of 80 shares = 2556.8
selling price of stocks = 2743.31
ROI =( net profit/ total investment ) * 100
ROI= ( ( 2743.31 - 2556.8) / 2556.8) * 100
ROI = (186.51/2556.8 ) * 100
ROI = 7.29 %
the mistake done by Bowen is that he has taken time (number of years = 6) in calculation which is not required and is resulting in the wrong answer