Xiao Ming's home is 5.25 kilometers away from the school. He goes to school by bike every day, and it takes 0.7 hours to go back and forth. How many kilometers does Xiao Ming ride on average per hour?
小明家距学校5.25千米，他每天骑车上学，往返一次共需0.7时，小明骑车平均每时行多少千米．
<gadget id="calculator">2 / 0.7</gadget>
<output>2.857143</output>

<gadget id="calculator">5.25 * 2.857143</gadget>
<output>15.000001</output>

<result>15.000001</result>