The road construction team repaired a road. On the first day, the whole length (4/7) was repaired, and the rest (3/5) was repaired on the second day. At this time, there were still 42 kilometers to be repaired. How long is the total length of this road? rice?
筑路队修一条公路，第一天修了全长的(4/7)，第二天又修了余下的(3/5)，这时还有42千米没有修，这段公路全长多少千米？
<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 - (4/7)</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(3/7) * (3/5)</gadget>
<output>9/35 = around 0.257143</output>

<gadget id="calculator">(3/7) - (9/35)</gadget>
<output>6/35 = around 0.171429</output>

<gadget id="calculator">42 / (6/35)</gadget>
<output>245</output>

<result>245</result>