2x^2=4x
I'm pretty sure this is it because there are only 2 like terms so you can't combine anything with 4x.

Actually Welcome to the Concept of the Equilateral Triangles.
Since, we know that, all the sides of a triangle are equal, hence it is a Equilateral triangle.
Equilateral triangle has one all angles equal to 60°.
so, major angle P = 60°
hence, 2x=60°
===> x = 30°