The distance between A and B is 60 kilometers. Xiaoqiang and Xiaohu ride bicycles from A to B. Xiaoqiang travels 15 kilometers per hour, and Xiaohu travels 20 kilometers per hour. After Xiaoqiang walked 10 kilometers, Xiaohu started. When Xiaohu catches up with Xiaoqiang, how many kilometers are there to B?
AB两地相距60千米，小强和小虎由A地骑车去B地，小强每时行15千米，小虎每小时行20千米．当小强走了10千米后，小虎才出发，当小虎追上小强时，距离B地还有多少千米？
<gadget id="calculator">20 - 15</gadget>
<output>5</output>

<gadget id="calculator">10 / 5</gadget>
<output>2</output>

<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<gadget id="calculator">60 - 40</gadget>
<output>20</output>

<result>20</result>