The number of boys in a class is twice the number of girls. If 20 boys are transferred and 15 girls are added, the number of girls is three times the number of boys. How many male and female students are there in this class?
某班男生人数是女生人数的2倍，若调走20名男生，增加15名女生，女生人数是男生人数的3倍．该班原有男女学生一共多少人．
<gadget id="calculator">20 * 3</gadget>
<output>60</output>

<gadget id="calculator">60 + 15</gadget>
<output>75</output>

<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<gadget id="calculator">6 - 1</gadget>
<output>5</output>

<gadget id="calculator">75 / 5</gadget>
<output>15</output>

<gadget id="calculator">15 * 2</gadget>
<output>30</output>

<gadget id="calculator">30 + 15</gadget>
<output>45</output>

<result>45</result>