A rope, (2/5) meter is used up for the first time, (1/2) meter is used up for the second time, and (1/10) meter is left, how many meters is this rope originally?
一根绳子，第一次用去(2/5)米，第二次用去(1/2)米，还剩(1/10)米，这根绳子原来长多少米？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

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

<result>1</result>