Hello, BG5965!

There are: . possible outcomes.A school principal needs to employ 9 staff members.

There are 4 lab assistants and 10 science teachers.

How many ways can he select 9 staff members if he needs at least one lab assistant?

The opposite of "at least one LA" is "noLA's" . . . that is, "all ST's."

. . There are: . ways to choose all ST's.

Therefore, there are: . ways to have at least one LA.