In the swimming pool, primary school students accounted for 30% of the swimming pool students. After another batch of students came, the total number of students increased by 20%, and primary school students accounted for 40% of the total number of students. What percentage of primary school students increased?
游泳池里，参加游泳的学生，小学生占30%，又来一批学生后，学生总数增加20%，小学生占学生总数的40%，小学生增加百分之几？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(6/5) * (2/5)</gadget>
<output>12/25 = around 0.48</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(12/25) - (3/10)</gadget>
<output>9/50 = around 0.18</output>

<gadget id="calculator">(9/50) / (3/10)</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>