Could you help me with this uncertainty please. Do we have to show in the exam to the examiner that we know the formula i.e for irredeemable loan totes Kd=I(1-t)/D or is it enough we just write the number straight away i.e Kd= 12(1-0.3)/92=9.1% using the numbers from the question.
This only applies to section C of the exam (because in sections A and B, nobody will look at your workings).
In section C it is fine to write down the numbers straight away. Just make sure that your workings are clear in case you make a mistake in the arithmetic. If it is clear what you are trying to do then you will still get most of the marks.