This tutorial takes you through a series of problems. This is the most difficult type of problem here. You have to go through the first few steps:
1. Decide if the reaction is SN1 or SN2 (see my other videos in this playlist for review).
2. Identify the nucleophile and what will substitute. (OH or OCH3 or Cl or what?)
2. Draw the stereochemistry
Racemic for SN1 reactions
Inversion for SN2 reactions