having trouble with SN1 and SN2 mechanism questions

https://preview.redd.it/gzjzzhiue9ug1.jpg?width=1052&format=pjpg&auto=webp&s=45bbfbfc9d1ba445f929fa69bb8123b0bf769096

everytime i think i understand how to do one of these questions i just get confused again, would really apprieciate any kind of guiding in how im supposed to go about these questions, most videos i find are only on the more basic type of question