well, the opening price was "x", which oddly enough is the 100%, however during the trading of the day the company gained 3.5%, so that'd be 100% + 3.5% = 103.5%, and we know that that is 16.56, so
[tex]\begin{array}{ccll} amount&\%\\ \cline{1-2} x&100\\ 16.56&103.5 \end{array}\implies \cfrac{x}{16.56}=\cfrac{100}{103.5}\implies 103.5x=1656 \\\\\\ x=\cfrac{1656}{103.5}\implies x=16[/tex]
