The Sum of the Angles of Any Four-Sided Figure (Called $360 ^ { \circ }$

Multiple Choice

The sum of the angles of any four-sided figure (called a quadrilateral ) is $360 ^ { \circ }$ . The quadrilateral shown has two equal base angles. Find x.

A) $x = 54 ^ { \circ }$
B) $x = 61 ^ { \circ }$
C) $x = 58 ^ { \circ }$
D) $x = 59 ^ { \circ }$
E) $x = 56 ^ { \circ }$