The first, second and third grades of the school held the "Singing the Motherland·Chorus" competition. The number of winners in the first and second grades accounted for (4/9) of the total number of winners, and the number of winners in the second and third grades accounted for (7/9) of the total number of winners. What percentage of the total number of winners are the number of winners in the second grade?
学校一、二、三年级举行"歌唱祖国•大合唱"比赛，一二年级获奖人数占获奖总人数的(4/9)，二三年级获奖人数占获奖总人数的(7/9)．二年级获奖人数占获奖总人数的几分之几？
<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">7 / 9</gadget>
<output>7/9 = around 0.777778</output>

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

<gadget id="calculator">(4/9) + (-2/9)</gadget>
<output>2/9 = around 0.222222</output>

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