There are 60 students in the chorus team, and the ratio of the number of male and female students is 2:1. Later, some female students were added. At this time, the ratio of male and female students was 5:3. How many more female classmates?
合唱队共有60名同学，其中男、女同学人数的比是2：1．后来又增加了一些女同学，这时男、女同学的比是5：3．女同学增加了几人？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">60 * (2/3)</gadget>
<output>40</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">40 * (3/5)</gadget>
<output>24</output>

<gadget id="calculator">60 - 40</gadget>
<output>20</output>

<gadget id="calculator">24 - 20</gadget>
<output>4</output>

<result>4</result>