Hi. This is the solution to your qn. The method used for bii and biii are quite long as they are only worth 1 mark. Supposedly, you are to use the “ASTC” method. I chose to show you a different one because it is definitely a life saver in exams if you accidentally forget/unaware about “ASTC”, where you can still get to the answer and grab that 1 mark. Though the method shown here is an alternative for you, you’re encourage to understand and remember “ASTC” so you’re well equipped with both methods to solve questions like this in future. I leave it to the other tutors for the “ASTC” one. If you find my solution helpful, please give it an upvote. Thanks. :)

1