At a party, there are 50 people. 30% of them are boys. How many girls are at this party?
There are 50 * 30/100 = 
<gadget id="calculator">50*30/100</gadget>
<output>15</output>
15 boys at that party.
That means there are 50 - 15 = 
<gadget id="calculator">50-15</gadget>
<output>35</output>
35 girls.

<result>35</result>