[tex]\boxed{\begin{array}{c|c|c|c}\boxed{\bf Element}&\boxed{\bf No\:of\:moles}&\boxed{\bf Sample\:ratio}&\boxed{\bf Simplest\:ratio}\\ \sf P&\sf \dfrac{15.5}{31}=0.5 &\sf \dfrac{0.5}{0.5}=1 &\sf 1 \\ \sf O&\sf \dfrac{20}{16}=1.2&\sf \dfrac{1.2}{0.5}=2.4 &\sf 2\end{array}}[/tex]
Empirical formula