Start with
[tex] 5x+8y = 6\pi [/tex]
Subtract 5x from both sides:
[tex] 8y = 6\pi-5x [/tex]
Divide both sides by 8:
[tex] y = \dfrac{6\pi-5x}{8} [/tex]
This is the expression solved for y, because we wrote an equivalent expression with y alone on the left hand side, and an expression not involving y on the right hand side
