To build a road, the first time the whole road was built (1/4), the second time the whole road was repaired (2/7), the second time was 2 kilometers longer than the first time, how long is this road? (column equation solution)
修一条公路，第一次修了全程的(1/4)，第二次修了全程的(2/7)，第二次比第一次多修了2千米，这条路有多长？(列方程解答)
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(2/7) - (1/4)</gadget>
<output>1/28 = around 0.035714</output>

<gadget id="calculator">2 / (1/28)</gadget>
<output>56</output>

<result>56</result>