Given the figure of a polygon that has 4 sides
So, the sum of the interior angles = 360
But the given angles are the supplementary angles for the polygon
so, the angles of the polygon will be as follow:
180 - 6x
180 - 5x
180 - (x+16)
180 - (3x-1)
the sum of the angles = 360
So, we can write the following equation:

Solve the equation to find (x), combine the like terms:

So, the answer will be x = 23