piece of iron wire, cut the full length (5/9) for the first time, the ratio of the length of the second cut to the length of the first cut is 9:20, there are 7 meters left, what is the total length of this piece of iron wire rice
一段铁丝，第一次剪下全长的(5/9)，第二次剪下的长度与第一次剪下的长度的比是9：20，还剩7米，这段铁丝全长多少米
<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">(5/9) * (9/20)</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>