Xiao Ming's brother rides a motorcycle from home to his grandfather's house 156 kilometers away. It is known that the departure time is 11:00 am and the arrival time is 1:00 pm. How many kilometers does Xiao Ming's brother drive on average per hour?
小明的哥哥骑摩托车从家出发去156千米外的爷爷家，已知出发的时间为上午11：00，到达时间为下午1：00，小明的哥哥平均每小时行驶多少千米？
<gadget id="calculator">156 / 2</gadget>
<output>78</output>

<result>78</result>