There are 43 students in a certain class, 13 girls, and how many girls are transferred later. At this time, the number of girls accounts for 40% of the whole class.
某班有学生43人，女生13人，后来又转来多少个女生，这时女生数占全班人数的40%．
<gadget id="calculator">43 - 13</gadget>
<output>30</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">30 / (3/5)</gadget>
<output>50</output>

<gadget id="calculator">50 - 43</gadget>
<output>7</output>

<result>7</result>