There is a wire, the full length (2/5) is used for the first time, 8 meters is used for the second time, and 1 meter (3/4) of this wire is used for the second time, the original length of this wire is How much rice.
有一根电线，第一次用去全长的(2/5)，第二次用去8米，两次一共用去这根电线的(3/4)还多1米，这根电线原来长多少米．
<gadget id="calculator">8 - 1</gadget>
<output>7</output>

<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(3/4) - (2/5)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">7 / (7/20)</gadget>
<output>20</output>

<result>20</result>