[tex]\bf \stackrel{5}{~~\begin{matrix} 20 \\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~} \times \cfrac{3}{~~\begin{matrix} 4\\[-0.7em]\cline{1-1}\\[-5pt]\end{matrix}~~}\implies 5\times 3\implies 15[/tex]
