[tex]\large \mathfrak{Solution : }[/tex]
The given pair of angles are vertical opposite angle pair so, they are equal. i.e
- [tex](x + 90)\degree = 4x\degree[/tex]
- [tex](4x - x) \degree= 90\degree[/tex]
- [tex]3x\degree = 90\degree[/tex]
- [tex]x\degree = \dfrac{90\degree}{3\degree} [/tex]
- [tex]x\degree = 30\degree[/tex]
