For a batch of goods, its (2/9) was shipped out on the first day, and its (4/9) was shipped out on the second day, and how much of it was left unshipped.
一批货，第一天运走了它的(2/9)，第二天运走了它的(4/9)，还剩下它的多少没运．
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">(2/9) + (4/9)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>