You pass the x in one side and numbers to the other side
8x-5x=58-4
add and subtract
3x=54
divide by 3
x=18
Given:
A figure of a quadrilateral.
To find:
The measures of angle 1 and angle 2.
Solution:
The given figure has two pairs of congruent adjacent sides. So, the quadrilateral in the figure is a kite.
We know that the diagonals of a kit are perpendicular to each other at the point of intersection.

According to the angle sum property, the sum of all interior angles of a triangle is 180 degrees.




Therefore, the correct option is C.