There are two ways to do it:
1) Simpler Way (solving it indirectly):
Find the total number of committees and then subtracts the number of committees which are all girls, as
OR
2) Solving it directly:
Hello, wikji!
Who assigned this problem?
. . In fact, who wrote it?
A school has 480 girls and 520 boys. How many committees of five
can be made if at least one boy must be on each committee?
There are: . possible committes.
The opposite of "at least one boy" is "no boys" (all girls).
There are: . all-girl committees.
There are about: . (eight trillion) committees with at least one boy.