There is an iron wire, 20 meters are used for the first time, and the remaining (1/6) is used for the second time, and finally (1/3) of the full length is left unused. How long is this iron wire in meters?
有一根铁丝，第一次用去20米，第二次用去了余下的(1/6)，最后还剩下全长的(1/3)没有用，这根铁丝长多少米？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 - (1/6)</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">(1/3) / (5/6)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(2/5) * (1/6)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 - (1/3) - (1/15)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">20 / (3/5)</gadget>
<output>100/3 = around 33.333333</output>

<result>100/3 = around 33.333333</result>