For a barrel of oil, the first time the barrel of oil was poured out (4/9), the second time the barrel of oil was poured less than the first time (1/9), the total amount of the barrel of oil was poured twice How much? How much is left?
一桶油，第一次倒出这桶油的(4/9)，第二次比第一次少倒了这桶油的(1/9)，两次一共倒了这桶油的几分之几？还剩下几分之几没倒？
<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">3 / 9</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(4/9) + (1/3)</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">1 - (7/9)</gadget>
<output>2/9 = around 0.222222</output>

<result>2/9 = around 0.222222</result>