[tex]\begin{gathered} y=mx+b \\ where \\ m=\text{slope} \\ b=y-\text{intercept} \end{gathered}[/tex]
Therefore,
[tex]m=\frac{-3+5}{5-0}=-\frac{2}{5}[/tex][tex]\begin{gathered} -5=-\frac{2}{5}(0)+b \\ b=-5 \end{gathered}[/tex][tex]y=-\frac{2}{5}x-5[/tex]
when y =-7
[tex]\begin{gathered} -7=-\frac{2}{5}x-5 \\ -7+5=-\frac{2}{5}x \\ -2=-\frac{2}{5}x \\ -10=-2x \\ x=\frac{-10}{-2} \\ x=5 \end{gathered}[/tex]
