A wire is cut off (1/4) and then connected to 12 meters, the result is longer than the original (1/3). How long is this wire originally?
一根电线截去(1/4)后再接上12米，结果比原来长(1/3)．这根电线原长多少米？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/4) + (1/3)</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">12 / (7/12)</gadget>
<output>144/7 = around 20.571429</output>

<result>144/7 = around 20.571429</result>