There is a ribbon, the full length (2/5) is used for the first time, and 6 meters is used for the second time. At this time, half of the ribbon is left. How many meters is the original length of the ribbon?
有一根丝带，第一次用去全长的(2/5)，第二次用去6米，这时丝带还剩一半，这条丝带原来长多少米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">1 - (1/2) - (2/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">6 / (1/10)</gadget>
<output>60</output>

<result>60</result>