AB and CD are interesting lines
Therefore, the angles formed will be equal (vertically opposite angles).
Hence,
[tex](5x - 10) = (3x + 40)[/tex]
Now,
[tex]5x - 10= 3x + 40[/tex]
[tex]5x - 3x = 40 + 10[/tex]
[tex]2x = 50[/tex]
[tex]x = \frac{50}{2} [/tex]
[tex]x = 25[/tex]
