Visit grandpa. On Sunday, Xiao Liang went to visit his grandpa. If you go there by car, it will take 1.5 hours to walk back; if you take a car both ways, it will take 0.5 hours. According to this calculation, how much time will it take to walk back and forth?
看望爷爷．星期天，小亮去看望爷爷．如果去时乘车，回来步行共需要1.5h；如果往返都乘车，需要0.5h．照这样计算，往返都步行要多少时间？
<gadget id="calculator">0.5 / 2</gadget>
<output>0.25</output>

<gadget id="calculator">1.5 - 0.25</gadget>
<output>1.25</output>

<gadget id="calculator">1.25 * 2</gadget>
<output>2.5</output>

<result>2.5</result>