This diagram doesn't make sense considering triangles have 180 degrees but as far as I can tell, there is no law in my math.
Because the unknown angles in the bottom triangle are the same as the angles in the top triangle, 4x must equal 2x+156
4x=2x+156
minus 2x from each side:
2x=156
2x is in the equation so B = 156+156 or 312.
Hope this helps :)
