A class contains 10 boys and 15 girls.
8 can go to a local castle, 7 can go to the theatre, the remainning 10 will go to the museum.
In how many ways can the class be divided for their activity
day if the group going to the theatre must consist of 4 girls and 3 boys?
Choose 4 girls to go to the theatre: . ways.
Choose 3 boys to go to the theatre: . ways.
The other 18 students are divided into a group of 8 and a group of 10.
(Their genders do not matter.) .There are: . ways.
Therefore, there are: . ways.