Maximizing Total Revenue

[TheNextOne]

A bank has two types of branches. A satellite branch employs 3 people and generates a daily revenue of $10,000. A full-service branch employs 6 people and generates a daily revenue of $18,000. The bank wishes to open at most 25 new branches, and to hire at most 120 new employees. How many branches of each type should the bank open in order to maximize the total daily revenue?

I have been stuck on this question for quite a while now. Can I solve this using larange multiplier? This is what I have tried so far:

I made the equation:

TR= 3qS-6qF+8,000
and the constratint
qS+qF-25 = 0

It does not seem to be working. Can anybody point me in the right direction?

 

[Gene]

Well,
TR = 10S+18F (in thousands)
S+F < 25
3S+6F < 120
if you graph those inequalities you get 4 points (S,F)
(0,0),(0,20),(10,15) and (25,0)
Try them in TR= to find max TR