A car drives from Dongcheng to Xicheng, travels 42 kilometers per hour, and arrives at City B in 5 hours; it takes 4 hours to return, how many kilometers per hour on average? (Solve with ratio)
一辆汽车从东城开往西城，每小时行42千米，5小时到达乙城；返回时用了4小时，平均每小时行多少千米？(用比例解)
<gadget id="calculator">42 * 5</gadget>
<output>210</output>

<gadget id="calculator">210 / 4</gadget>
<output>105/2 = around 52.5</output>

<result>105/2 = around 52.5</result>