A rope, cut off (1/5) for the first time, and cut off the rest (2/3) for the second time, how much of the rope is left at this time.
一根绳子，第一次截去(1/5)，第二次截去余下的(2/3)，这时还剩下这根绳子的多少．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

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

<gadget id="calculator">(4/5) * (2/3)</gadget>
<output>8/15 = around 0.533333</output>

<gadget id="calculator">1 - (1/5) - (8/15)</gadget>
<output>4/15 = around 0.266667</output>

<result>4/15 = around 0.266667</result>