A water canal in Xinhua Village was built. (3/10) kilometers were built on the first day, (2/5) kilometers were repaired on the second day, and (3/10) kilometers remained. How many kilometers will this canal be after it is completed?
新华村修一条水渠，第一天修了(3/10)千米，第二天修了(2/5)千米，还剩(3/10)千米，这条水渠修成后长多少千米？
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

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

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

<result>1</result>