A car delivers goods to a mountainous area, travels 42 kilometers per hour, and arrives in (6/7) hours. It only took (3/4) hours to go back the same way, how many kilometers per hour on average when returning?
一辆汽车往山区送货，每小时行42千米，(6/7)小时到达．原路返回时只用了(3/4)小时，返回时平均每小时行多少千米？
<gadget id="calculator">6 / 7</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(6/7) / (3/4)</gadget>
<output>8/7 = around 1.142857</output>

<gadget id="calculator">42 * (8/7)</gadget>
<output>48</output>

<result>48</result>