A=19
Explanation
Vertical Angles are the angles opposite each other when two lines cross
Step 1
let
[tex]A=B[/tex]where
[tex]\begin{gathered} A=3x+13 \\ B=5x+9 \end{gathered}[/tex]Step 2
replace,
[tex]\begin{gathered} A=B \\ 3x+13=5x+9 \end{gathered}[/tex]Step 3
solve for x
[tex]\begin{gathered} 3x+13=5x+9 \\ 13-9=5x-3x \\ 4=2x \\ x=\frac{4}{2} \\ x=2 \end{gathered}[/tex]Step 4
finally, replace the valur of x= 2 to find A
[tex]\begin{gathered} A=3x+13 \\ A=3\cdot2+13 \\ A=6+13 \\ A=19 \end{gathered}[/tex]I hope this helps you
