100 students attended a carnival.
less than 10 years old: 60% of the students = 60% * 100 = 60/100 * 100 = 60 students
over 6 years old: 75% of the students = 75% * 100 = 75/100 * 100 = 75 students
If you would like to know how many children were between 6 and 10 years old, you can calculate this using the following steps:
If there are 75 children over 6 years old, that means that there must be 25 children (100 - 75) less than 6 years old, so if there are 60 children less than 10 years old, that means that there are 60 - 25 = 35 children over 6 years old.
The correct result would be 35 children.