After measuring an angle, after the center point is aligned with the vertex, one side of the angle is found facing the outer scale "100" on the protractor, and the other side is facing the outer scale "30". What is the angle in degrees?
度量一个角，中心点对准顶点后，发现角的一条边对着量角器上外圈刻度"100"，另一条边对着外圈刻度"30"，这个角是多少度．
<gadget id="calculator">100 - 30</gadget>
<output>70</output>

<result>70</result>