Measure an angle, one side of the angle is facing the inner circle scale "180" on the protractor, and the other side is facing the inner circle scale "60", what is the angle in degrees?
度量一个角，角的一条边对着量角器上内圈刻度"180"，另一条边对着内圈刻度"60"，这个角是多少度．
<gadget id="calculator">180 - 60</gadget>
<output>120</output>

<result>120</result>