A piece of iron wire is cut off by (2/3) meters and then welded on (1/4) meters. Now the length of the iron wire is (7/12) meters. How many meters was the original length of the iron wire? (column equation solution)
一根铁丝，截去(2/3)米后又焊接上(1/4)米，现在这根铁丝长(7/12)米，这根铁丝原来长多少米？(列方程解答)
<gadget id="calculator">7 / 12</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(2/3) - (1/4)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">(7/12) + (5/12)</gadget>
<output>1</output>

<result>1</result>