The sentence that requires revision to maintain a formal style is:
"Quakers like William Penn wouldn't pay taxes to support wars because they were against it, and this made people angry."
To revise this, you can replace "wouldn't" with "would not" and "this made people angry" with a more formal phrase, such as "which caused significant dissatisfaction among the populace."
A revised version could read: "Quakers like William Penn would not pay taxes to support wars because they were opposed to it, which caused significant dissatisfaction among the populace."