An engineering team repaired a section of road. (1/4) of the road was repaired in the first week, and (2/7) of the road was repaired in the second week. The second week repaired 2 kilometers more than the first week. How long is this road in kilometers? (Solution of column equation)
某工程队修一段公路，第一周修了这段公路的(1/4)，第二周修了这段公路的(2/7)，第二周比第一周多修2千米．这段公路全长多少千米？(列方程解)
<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>