When two angles are complementary, it means that they add up to 90°.
This way,
[tex]m\angle1+m\angle2=90[/tex]Thereby,
[tex](x+3)+(4x-8)=90[/tex]Solving for x,
[tex]\begin{gathered} (x+3)+(4x-8)=90 \\ \rightarrow x+3+4x-8=90 \\ \rightarrow5x-5=90 \\ \rightarrow5x=95\rightarrow x=\frac{95}{5} \\ \\ \Rightarrow x=19 \end{gathered}[/tex]Answer: Option B
