Solve for b:
Expand the right hand side using distributive property:
[tex]7=-11+3b+15[/tex]Add like terms:
[tex]7=3b+4[/tex]Subtract 4 from both sides:
[tex]\begin{gathered} 7-4=3b+4-4 \\ 3=3b \end{gathered}[/tex]Divide both sides by 3:
[tex]\begin{gathered} \frac{3}{3}=\frac{3b}{3} \\ b=1 \end{gathered}[/tex]