To solve for y, we first write the equation
[tex]5x-8y=40[/tex]subtracting 5x from both sides gives
[tex]5x-8y-5x=40-5x[/tex][tex]-8y=40-5x[/tex]Finally, dividing both sides by -8 gives
[tex]y=\frac{40-5x}{-8}[/tex][tex]y=\frac{40}{-8}-\frac{5x}{-8}[/tex][tex]y=-5+\frac{5}{8}x[/tex]or more neatly
[tex]\boxed{y=\frac{5}{8}x-5.}[/tex]