Answer: A: 20
Step-by-step explanation: The sum of all the angles in a 4-sided figure is always 360°. We know from the diagram that one of the angles is 120° and the other two are 90° as shown by the red indicators. Adding these up, we get 300°, which is 60° away from our total. Thus, 3x, the final angle, must be 60°. We can get x from this by dividing 3x by 3 to get 20°.
