Solve for y
[tex]4x+3y=-21[/tex]Subtract 4x both sides
[tex]\begin{gathered} 4x+3y-4x=-21-4x \\ 3y=-21-4x \\ \end{gathered}[/tex]Divide by 3 into both sides
[tex]\begin{gathered} \frac{3y}{3}=-\frac{21}{3}-\frac{4x}{3} \\ y=-7-\frac{4}{3}x \\ by\text{ reordering} \\ y=-\frac{4}{3}x-7 \end{gathered}[/tex]Answer:
[tex]y=-\frac{4}{3}x-7[/tex]