Answer:
66.
Step-by-step explanation:
The quadrilateral from the picture is a parallelogram, meaning that his opposite sides and angles are equal. Therefore the angle x is similar to its opposite angle.
We know the value of two of the angles of the triangle formed by the parallelogram's diagonal. All we need to do is calculate the third one which would be equal to its opposite x.
The total value of all three angles of a triangle is 180. We must take away the two given values from the total of 180 in order to calculate the third angle's value.
180 - 63 - 31 = 66
x = 66