For (a) you are going to have to be more specific because the examiners answer does explain. Obviously there is no point in my simply writing the same as him, but if you say which part is not clear to you then I will try and help.
For training and development costs, the question says that in the first year they are 80% of production and selling costs. So 80% x 511.5 = 409.2
In the second year, the question says that they fall to 20%, so 20% x 844 = 168.8