Jianshe Elementary School organizes a chorus team, with 20 participants in the sixth grade, 25% more participants in the fifth grade than the sixth grade, and 12% fewer participants in the fourth grade than the fifth grade. How many people are there in the fourth and fifth grades in the chorus?
建设小学组织合唱队，六年级有20人参加，五年级参加的人数比六年级多25%，四年级参加的人数比五年级少12%．合唱队中四、五年级总共有多少人？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + (1/4)</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">20 * (5/4)</gadget>
<output>25</output>

<gadget id="calculator">12 / 100</gadget>
<output>3/25 = around 0.12</output>

<gadget id="calculator">1 - (3/25)</gadget>
<output>22/25 = around 0.88</output>

<gadget id="calculator">25 * (22/25)</gadget>
<output>22</output>

<gadget id="calculator">22 + 25</gadget>
<output>47</output>

<result>47</result>