To build a road, the whole road (2/5) was repaired in the first month, and 30 kilometers were repaired in the second month, which happened to be the full length (3/5). How many kilometers were repaired in the first month?
修一条路，第一个月修了全路的(2/5)，第二个月修了30千米，正好修了全长的(3/5)，求第一个月修了多少千米？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">30 / (3/5)</gadget>
<output>50</output>

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

<gadget id="calculator">50 * (2/5)</gadget>
<output>20</output>

<result>20</result>