16. Find x.

The line AM is tangent to the circle at point A. Therefore, OA is perpendicular to AM, so angle OAM = 90 degrees. The central angle subtended by arc AB is 140 degrees. The inscribed angle subtended by arc AB is angle ACB, where C is a point on the major arc AB. Angle ACB = 140 / 2 = 70 degrees. In triangle OBM, OB = OA (radii). Angle AOB = 140 degrees. Angle BOM = 180 - 140 = 40 degrees. In triangle OBM, angle OMB = angle OBM. Angle BOM + angle OMB + angle OBM = 180. 40 + 2 * angle OMB = 180. 2 * angle OMB = 140. angle OMB = 70 degrees. Angle x is angle OMB. Therefore, x = 70 degrees.