A calligraphy competition was held in a certain city (all contestants won prizes), the number of people who won the first and second prizes accounted for (2/5) of the total number of winners, and the number of people who won the second and third prizes accounted for (9/10) of the total number of winners, What is the percentage of the total number of people who won the first prize less than those who won the second prize?
某市举行书法竞赛(参赛者均获奖)，获一、二等奖的人数占获奖总人数的(2/5)，获二、三等奖的人数占获奖总人数的(9/10)，获一等奖比获二等奖的少占总人数的多少．
<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">1 - (9/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(2/5) - (1/10) - (1/10)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>