I think the hardest points of viva voce is to convince your viewers that your method is correct and to make them understand. You have to keep it as simple as possible, so that people can understand.
I learnt that explaining a question is much harder than solving it. If we just read out the solutions, the listener might not have the same perspective of viewing the question as you, so he/she may not be able to understand.
Done by: Jerome Heng Hao Xiang (S1-04)