Wen Wen went to his classmate's house, if he took the car both times, it would take 46 minutes; if he went there by car and walked back, it would take 78 minutes. How many minutes does it take Wenwen to walk back?
文文去同学家，如果往返都乘车，要用46分钟；如果他去时乘车，回来时步行，要用78分钟．文文回来步行用多少分钟？
<gadget id="calculator">46 / 2</gadget>
<output>23</output>

<gadget id="calculator">78 - 23</gadget>
<output>55</output>

<result>55</result>