Answer: x = 195
Step-by-step explanation
The four angles of a quadrilateral always add to 360 degrees. This is because we can subdivide the quadrilateral into two triangles, and each triangle provides an angle sum of 180 degrees. So 180+180 = 360.
Add up the angles shown in the diagram. Set the sum equal to 360 so we can solve for variable x.
40+87+38+x = 360
165+x = 360
x = 360-165
x = 195