Xiao Fang rode a bicycle and covered 42 kilometers in the first 3 hours, and 63 kilometers in the next 4 hours. What is the correct formula for finding the average speed of Xiaofang riding a bicycle
小方骑自行车，前3小时行了42千米，后4小时行了63千米．求小方骑车的平均速度的正确算式是多少
<gadget id="calculator">42 + 63</gadget>
<output>105</output>

<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">105 / 7</gadget>
<output>15</output>

<result>15</result>