The road construction team built a 20-kilometer road. The full length (1/5) was repaired on the first day, and the full length (1/4) was repaired on the second day. How many kilometers were repaired in two days?
筑路队修一条20千米的公路．第一天修了全长的(1/5)，第二天修了全长的(1/4)，两天一共修了多少千米？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">(1/5) + (1/4)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">20 * (9/20)</gadget>
<output>9</output>

<result>9</result>