[tex]\begin{gathered} y-\text{intercept ocurrs when x=0. By substituying x=0 in all the equations, one has:} \\ -3y=15\Rightarrow y=\frac{15}{-3}\Rightarrow y=-5 \\ -8y=-40\Rightarrow y=\frac{-40}{-8}\Rightarrow y=5 \\ -y=10\Rightarrow y=-10 \\ 4y=20\Rightarrow y=\frac{20}{4}\Rightarrow y=5 \\ -y=5\Rightarrow y=-5 \\ y=-1 \end{gathered}[/tex]
