Books on Writing Short Stories/Persuasive Essays

hi everyone! im not sure if this is the right sub for this post, so sorry if it isn’t. im sitting an exam in about three months and i need some advice/book suggestions. the exam covers math, reading, writing, and reasoning, but im currently focusing on writing. you get twenty minutes to hand write a creative short story from a prompt they give you, and a persuasive essay from a prompt too. i was wondering whether anyone had any books that helped/worked for generating ideas/interesting premise, structuring a story, characters, description, or just short story writing in general. ive struggled to apply the techniques in books i have read since the exam provides a prompt for you, and i struggle to apply it well or even think of a interesting idea. also any books on writing persuasive essays would help too, thank you!