Question 1102725
You are choosing  3 of 7 teachers, that can be done in  7C3 = (7!)/(3!*4!) = 35 ways
and you are choosing 4 of 9 students, that can be done in  9C4 = (9!)/(4!*5!) = 126 ways

The total committees that can be formed is then  35*126 = <b>4410</b>