To build a road, 30% of the road was repaired for the first time, 4 kilometers were used for the second repair, and (2/5) of the road was used for the third time, leaving 3 kilometers left. How many kilometers was this road originally?
修一条路，第一次修去了这条路的30%，第二次修去了4千米，第三次用去了这条路的(2/5)，还剩3千米．这条路原来有多少千米？
<gadget id="calculator">4 + 3</gadget>
<output>7</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (3/10) - (2/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">7 / (3/10)</gadget>
<output>70/3 = around 23.333333</output>

<result>70/3 = around 23.333333</result>