After using up (1/3) meter of a rope, there are 4 meters left, what is the original length of the rope?
一根绳子用去(1/3)米以后，还剩4米，这根绳子原来长多少米．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">4 + (1/3)</gadget>
<output>13/3 = around 4.333333</output>

<result>13/3 = around 4.333333</result>