jmc

There are $5$ days from May 1 to May 5. The number of bananas he eats each day is an arithmetic sequence. He eats $n$ bananas on May 5, and $n-4(6)=n-24$ bananas on May 1. The sum of this arithmetic sequence is equal to $100$. $$\begin{array}{rl}\frac{n+n-24}{2}\cdot 5& =100\\ n-12& =20\\ n& =\boxed{32}\end{array}$$