There are $5$ days from May $1$ to May $5$ . If we set the first day as $n$, the second day can be expressed as $n+6$, the third as $n+12$, and so on, for five days. The sum $n+(n+6)+(n+12)+(n+18)+(n+24)$ is equal to $100$ , as stated in the problem. We can write a very simple equation, that is: $5 n+60=100$. Now all we do is just solve. $5 n=40$, so Big Al eats 8 bananas on the first day. The fifth day, $n+24$, is then 32 , which is your answer. 
Big Al, the ape, ate $100$ bananas from May $1$ through May $5$ . Each day he ate six more bananas than on the previous day. How many bananas did Big Al eat on May $5$ ? (2005 AMC 8 Problems, Question \#12) 
Options:
A: $$20$$ 
B: $$22$$ 
C: $$30$$ 
D: $$32$$ 
E: $$34$$ 