The ratio of the number of girls to boys in the sixth grade of the experimental primary school is 2:3. It is known that there are 30 boys, how many girls are there?
实验小学六年级女生与男生人数的比是2：3，已知男生有30人，女生有多少人？
<gadget id="calculator">30 / 3</gadget>
<output>10</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<result>20</result>