There are 20 girls in Class 1, and the ratio of boys to girls is 5:4. How many people are there in the class?
六1班有女生20人，男、女生人数的比是5：4．全班一共有多少人？
<gadget id="calculator">5 + 4</gadget>
<output>9</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">20 / (4/9)</gadget>
<output>45</output>

<result>45</result>