The distance between A and B is 35 kilometers. Xiao Zhang and Xiao Li want to go from A to B. They only have one bicycle. Xiao Zhang walks first, and Xiao Li rides first, and they start at the same time. Xiao Zhang's walking speed is 5 kilometers per hour, and Xiao Li's walking speed is 4 kilometers per hour. Both are cycling at a speed of 20 kilometers per hour. So how many hours will it take for both of them to travel from A to B?
甲、乙两地相距35千米，小张、小李都要从甲地去乙地，他们只有一辆自行车，小张先步行，小李先骑车，同时出发．小张步行的速度是每小时5千米，小李步行的速度是每小时4千米．两人骑车的速度都是每小时20千米．那么两人都从甲地到乙地，最少要共用多少小时？
<gadget id="calculator">16 + 3</gadget>
<output>19</output>

<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">35 / 20 / 7</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">19 * (1/4)</gadget>
<output>19/4 = around 4.75</output>

<result>19/4 = around 4.75</result>