this is a cool shape. it has 7 sides.
here's a formula: the sum of interior angles in a shape with x number of sides is 180*(x-2)
in this case, x is 7
so, we have 180*(7-2) = 900 as the sum of all interior angles
so 139 + 121 + 125 + 126 + 158 + 120 + x = 900
now you solve for x (but i'll do it because you are lazy)
789 + x = 900
x = 111
woohooo