To build a canal with a length of 5 kilometers, it was built on the first day (3/10), and the rest (2/5) was repaired on the second day. How many meters are left to be repaired?
修一条长5千米的水渠，第一天修了(3/10)，第二天修了余下(2/5)，还有多少米没修？
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (3/10)</gadget>
<output>7/10 = around 0.7</output>

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

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">5 * (7/10) * (3/5)</gadget>
<output>21/10 = around 2.1</output>

<result>21/10 = around 2.1</result>