In a class where there are as many girls as boys, 2/5 of the boys and 1/2 of the girls went to a local fair. What fraction of the students in the class did not go to the local fair?
The answer is 1/10 of the class did not go to the local fair.
Solution:
2/5 + 1/2 = 9/10
10/10 is the fraction of all the students, both those who go and did not go.
10/10 - 9/10 = 1/10