use 180(x-2) to work out sum of interior angles
x being the number of sides of the shape
as you can see in the image the shape is an irregular hexagon
180(6-2)
180x4
Sum of interior angles is 720
To work out x add up all interior angles
Therefore that would be
158+123+167+x+107+90(since a right angle is always 90)
158+123+167+107+90=645
Now do 720-645 to get 75 degrees as your last angle