Xiaoming's family went to climb the mountain. It took 4 hours to go up the mountain and 3 hours to go down the mountain. If the distance from the foot of the mountain to the top of the mountain is 7 kilometers, what is the average speed of Xiaoming's family going up and down the mountain?
小明一家去登山，上山花了4小时，下山用了3小时．如果山脚到山顶的路程是7千米，小明一家上下山的平均速度是多少？
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">7 * (2/7)</gadget>
<output>2</output>

<result>2</result>