It takes 40 minutes for Xiaohong to walk back and forth from her home to the bookstore, and 27 minutes if she rides a bicycle from home to the bookstore and then walks home. How many minutes would it take if she cycled back and forth.
小红从家到书店这段路程如果步行往返需要40分钟，如果她从家骑自行车去书店，然后步行回家需要27分钟．如果她骑自行车往返则需要多少分钟．
<gadget id="calculator">40 / 2</gadget>
<output>20</output>

<gadget id="calculator">27 - 20</gadget>
<output>7</output>

<gadget id="calculator">7 * 2</gadget>
<output>14</output>

<result>14</result>