Here's what I've got:

Max: .2s + .25m (OBJECTIVE FUNCTION)

subject to: (CONSTRAINTS)

s + m ≤ 70

s ≤ 50

m ≤ 30

s,m ≥ 0

Then, it sounds like you are using the Corner Point Theorem (I am assuming, since you asked for vertices). So you would just graph the above constraints to find the feasible region, and then evaluate the objective function at each of the corner points:

Corner points (Vertices):

a = (0,0)

b = (50,0)

c = (0,30)

d = (40,30)

e = (50,20)

So evaluating your objective function at all of these points yields a maximum profit at corner point d=(40,30):

Max (C?) = $15.50 per day

with Snickers=40 and M&Ms=30

I hope that made sense....let me know if anything is unclear.