To solve it, you should write them as whole fractions then convert the answer to a mixed one, much easier I guess, so:
4 1/2 = (8+1)/2 = 9/2
1 1/4 = (4+1)4 = 5/4
So 9/2 / 5/4 = a b/c
9/2 x 4/5 = a b/c
36/10 = a b/c
18/5 = a b/c
Now convert it:
3 3/5 = a b/c
So a=3, b=3, and c=5
So the correct answer is b.