Please take time to get to know the oxidation states of carbon.
http://lennoxtutoring.com/2012/04/18/oxidation-states-of-carbon/Quite literally I have 6 students taking the final roundup in Organic Chemistry who are still struggling with oxidation states. When I show them just how many points on exams this knowledge can save them, they "feel" it.
What is the oxidation state of the carboxylic acid carbon? What is the oxidation state of toluene? How do they differ? By how many electrons do they differ? How many electrons "apart" are they? What process do you have to use to get one to the other? What reagents would you use?
Good luck!