The grocery store brought in a batch of cabbage, sold (2/9) of the total on the first day, and sold (1/18) less of the total on the second day than on the first day. What percentage of the total cabbage is sold in two days?
菜店运进一批白菜，第一天卖了总数的(2/9)，第二天比第一天少卖了总数的(1/18)．两天卖的白菜占总数的几分之几？
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">1 / 18</gadget>
<output>1/18 = around 0.055556</output>

<gadget id="calculator">(2/9) - (1/18)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/6) + (2/9)</gadget>
<output>7/18 = around 0.388889</output>

<result>7/18 = around 0.388889</result>