Teacher Zhang rides a bicycle from home to school at 15 kilometers per hour, and it takes 0.25 hours to get there. How many hours would it take him to walk 5 kilometers per hour instead?
张老师从家骑车到学校每小时行15千米，要用0.25小时到达．如果他改为步行，每小时走5千米，需要多少小时？
<gadget id="calculator">0.25 / 5</gadget>
<output>0.05</output>

<gadget id="calculator">15 * 0.05</gadget>
<output>0.75</output>

<result>0.75</result>