A camera and its leather case cost 240 yuan in total. This camera is 180 yuan more expensive than the leather case. How much is the leather case?
一架照相机和它的皮套共240元，这架照相机比皮套贵180元，皮套多少元．
<gadget id="calculator">240 - 180</gadget>
<output>60</output>

<gadget id="calculator">60 / 2</gadget>
<output>30</output>

<result>30</result>