Human: 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? Assistant:
Out of 100 students, half are girls and half are boys so there are 100/2 = 50 girls
There are 50 girls out of 100 students means there are 100-50 = 50 boys
20% of the 50 girls have dogs so they have .20*50 = 10 dogs
10% of the 50 boys have dogs so they have .10*50 = 5 dogs
The girls have 10 dogs and the boys have 5 dogs so together, they have 10+5 = 15 dogs