FRF7 Chapter 24 - Practice Question 1 (Multiple choice question) on IFRS 15

Good afternoon, Can you kindly help me in explaining how to arrive to the answer €4380. I have tried to arrive to the answer in several ways however I am really not finding the way to it. This is how I would answer the question Costs incurred plus to complete (5m +16m) * 30% = 6.3m Costs recognised in the prev year Aug 14 = 1.6m or Costs for Aug 14 (1.6+20) * 8%= 1.728 Therefore costs for Aug 15 should be (6.3m - 1.6m) = 4.7m or (6.3m-1.728m)= 4.57m however the answer is 4.38m in the multiple choice. Thank you.