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."
The use of "wouldn't" and the phrase "made people angry" contribute to an informal tone. A more formal revision could be:
"Quakers, including William Penn, refused to pay taxes to support wars due to their opposition to violence, which led to significant resentment among the populace."