A school has 100 students. Half of the students are girls, the other half are boys.  20% of the girls have dogs at home and 10% of the boys have dogs at home.  How many students own dogs?
Out of 100 students, half are girls and half are boys so there are 100/2 = 
<gadget id="calculator">100/2</gadget>
<output>50</output>
50 girls.
There are 50 girls out of 100 students means there are 100-50 = 
<gadget id="calculator">100-50</gadget>
<output>50</output>
50 boys
20% of the 50 girls have dogs so they have .20*50 = 
<gadget id="calculator">20*.01*50</gadget>
<output>10</output>
10 dogs
10% of the 50 boys have dogs so they have .10*50 = 
<gadget id="calculator">.10*50</gadget>
<output>5</output>
5 dogs.
The girls have 10 dogs and the boys have 5 dogs so together, they have 10+5 = 
<gadget id="calculator">10+5</gadget>
<output>15</output>
15 dogs.

<result>15</result>