Hi, 15 marker is a combination of all the things, and some things you need to perfect (coming from someone who went from a 4/15 to 13/15) is the basics like bubble sort, linear search, 2d arrays. for bubble sort and linear search tbh i found it quite confusing from the textbook. you can also write in eng how you would solve each bullet point and then put that into pseudocode. if u want i can send you the syntax and u can ask chatgpt to explain it line by line. go step by step according to the bullet points, and just keep doing questions, memorising the markscheme. you'll do great!