A 20 person classroom is filled with 40% girls. If 5 new boys join the classroom, what is the new percentage of girls in the class?
The number of girls in the classroom is 20 * 40% = 
<gadget id="calculator">20*40*.01</gadget>
<output>8</output>
8 girls.
Before new boys join, the number of boys in the classroom is 20 - 8 = 
<gadget id="calculator">20-8</gadget>
<output>12</output>
12 boys.
If 5 new boys join, the new number of boys is 12+5=17 boys and the new total is 20+5=25 total people.
The new percentage of girls in the class is 8 girls / 25 total people = 32%

<result>32</result>