hi,

see cengage books are complete package of 10+2 course. you may divide it in two parts according to the syllabus of 11th and 12th. however first of all complete the chapters of physics, chemistry and mathematics from text book, solve text book exercise , then after complete 3-4 chapters , solve cengage books problems. however I would suggest to give priority to 11th standard syllabus first, also clear your concepts and make short notes. make a routine for daily work and studies and strictly follow it.