we write an equation for each statement
$500 per month plus 4% commission on her total sales
[tex]y=500+0.04x[/tex]$400 per month plus 5% commission on total sales
[tex]y=400+0.05x[/tex]system, of equations is
[tex]\begin{gathered} y=500+0.04x \\ y=400+0.05x \end{gathered}[/tex]