Kaplan MA Performance Measurement - Capital Employed

Hi good morning, Appreciate your help with this question; Green division is one of many divisions in Colour plc. At its year-end, the fixed assets invested in Green were £30 million, and the net current assets were £5 million. Included in this total was a new item of plant that was delivered three days before the year end. This item cost £4 million and had been paid for by Colour, which had increased the amount of long term debt owed by Green by this amount. The profit earned in the year by Green was £6 million before the deduction of £1.4 million of interest payable to Colour. What is the most appropriate measure of ROI for the Green division? A 13.1% B 14.8% C 17.1% D 19.4% Now I understand that ROI = Pbit/ capital employed, however I am finding difficulty in understanding exactly the reasoning. I manged to find a past article on this website where you are explaining capital employed should be 35-4=31. The answer from the book agrees. Isnt capital employed either; - current assets + non- current assets - current liabilities or - long term liabilities + shareholders funds? So in this case is they purchased the machine (NCA) for 4 mil why to we subtract it in this case? I am genuinely confused at this point.. I would really appreciate if you can help clear up this issue as I cannot understand the actual reasoning. Thank you very much! Grateful for your time and efforts :)