There are 20 boys in Class 41, which is equivalent to (2/3) of girls. How many girls are there?
四一班有男生20人，相当于女生的(2/3)．女生有多少人？
<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">20 / (2/3)</gadget>
<output>30</output>

<result>30</result>