A certain city holds a mathematics competition, and there are a number of first, second and third prizes. The number of winners of the first and second prizes accounts for (2/5) of the total number of people, and the number of people who win the second and third prizes accounts for (2/5) of the total number of winners. 9/10), what percentage of the total number of winners are the second prize winners?
某市举办一次数学竞赛，设一、二、三等奖若干名，获一、二等奖的人数占总人数的(2/5)，获二、三等奖的人数占获奖总人数的(9/10)，获二等奖的人数占获奖总人数的几分之几？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</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">(2/5) + (-1/10)</gadget>
<output>3/10 = around 0.3</output>

<result>3/10 = around 0.3</result>