To determine how much Rob paid per share when he bought the stock two years ago, we first need to know what fraction of the current price he paid. You mentioned that the price when Rob bought the stock was some fraction of the current price per share, but did not specify that fraction.
Assuming the fraction is, for example, \( \frac{1}{x} \), we can express the purchase price (P) as follows:
\[ P = \frac{19.80}{x} \]
To provide a complete answer, I need the exact fraction or percentage that indicates what Rob paid compared to the current price. If you provide that, I can calculate the exact amount he paid per share.