A piece of iron wire, cut off the full length (5/9) for the first time, the ratio of the second cut to the first time is 9:20, leaving 7 meters, how many meters is the length of this iron wire?
一根铁丝，第一次剪去全长的(5/9)，第二次剪去的与第一次的比是9：20，剩下7米，这根铁丝长为多少米？
<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">9 / 20</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">(9/20) * (5/9)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (5/9) - (1/4)</gadget>
<output>7/36 = around 0.194444</output>

<gadget id="calculator">7 / (7/36)</gadget>
<output>36</output>

<result>36</result>