Uncle Zhang walked when he went to work and took a car when he returned home. He spent 1.5 hours on the road. If commuting and commuting by car, the whole journey will only take 0.5 hours; if commuting and commuting on foot, how many hours will the whole journey take?
张叔叔上班时步行，回家时乘车，在路上一共用了1.5小时．如果上、下班都乘车，全程只需要0.5小时；如果上、下班都步行，全程要用多少小时？
<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>