There are 21 boys and 18 girls in the third class of the sixth grade, and a girl is transferred later. At this time, what percentage of the class are girls?
六年级三班有男生21人，女生18人，后来又转来一名女生，这时女生占全班人数的百分之几？
<gadget id="calculator">18 + 1</gadget>
<output>19</output>

<gadget id="calculator">21 + 19</gadget>
<output>40</output>

<gadget id="calculator">19 / 40</gadget>
<output>19/40 = around 0.475</output>

<result>19/40 = around 0.475</result>