The school will hold an English speaking competition, and set up a number of first, second and third prizes. The total number of first and second prizes will account for 1/2 of the number of winners, and the total number of second and third prizes will account for 1/2 of the number of winners. (8/9), what percentage of the total number of winners of the first and third prizes accounted for the total number of winners?
学校要举行一次英语口语大赛，设一、二、三等奖若干名，获得一、二等奖的总人数占获奖人数的(1/2)，获得二、三等奖总人数占获奖人数的(8/9)，获一、三等奖的总人数占获奖总人数的几分之几？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">8 / 9</gadget>
<output>8/9 = around 0.888889</output>

<gadget id="calculator">1 - (8/9)</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">(1/2) + (1/9)</gadget>
<output>11/18 = around 0.611111</output>

<result>11/18 = around 0.611111</result>