Xiao Ming walked (12/21) kilometers in (2/7) hours, how many kilometers did he walk in an hour?
小明(2/7)小时走了(12/21)千米，他每小时走了多少千米．
<gadget id="calculator">12 / 21</gadget>
<output>4/7 = around 0.571429</output>

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

<gadget id="calculator">(4/7) / (2/7)</gadget>
<output>2</output>

<result>2</result>