Yuehua Primary School held a mathematics ability competition, with a number of first, second and third prizes, the first and second prizes accounted for (3/7) of the total number of winners, and the second and third prizes accounted for ( 9/10), what percentage of the total number of winners won the second prize?
跃华小学举行数学能力竞赛，设有一、二、三等奖若干名，获一、二等奖的占获奖总人数的(3/7)，获二、三等奖的占获奖总人数的(9/10)，获二等奖的占获奖总人数的几分之几？
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">9 / 10</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">(9/10) - 1</gadget>
<output>-1/10 = around -0.1</output>

<gadget id="calculator">(3/7) + (-1/10)</gadget>
<output>23/70 = around 0.328571</output>

<result>23/70 = around 0.328571</result>