[tex]\begin{gathered} 5y=ax-4\Rightarrow y=\frac{1}{5}ax-\frac{4}{5} \\ y=\frac{1}{5}ax-\frac{4}{5} \\ slope=\frac{1}{5}a \\ \text{if slope = 2, we have:} \\ 2=\frac{1}{5}a \\ \text{Multiply each side by 5, we have:} \\ a=2\cdot5=10 \\ a=10 \end{gathered}[/tex]
