Review the item:
Syed finally decided to clean out his disorganized book bag, old U.S. Government
handouts, math notes from Intermediate Algebra,
leaky ballpoint pens, and a smashed banana littered the inside.
Math notes from Intermediate Algebra is the second item in a series of four. Leaky ballpoint pens is the third item in the series. You need a comma to separate items in a series.