Dongdong rode a bike to grandma’s house, and traveled 12 kilometers per hour for 2 hours. It only took 1 hour to go home and return the same way. How many kilometers per hour did Dongdong travel to and from grandma’s house on average this time?
冬冬骑车到姥姥家，每小时行12千米，行了2小时，回家按原路返回只要1小时，冬冬这次到姥姥家来回平均每小时行多少千米？
<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">12 * 2 * (2/3)</gadget>
<output>16</output>

<result>16</result>