English Coursework Explanation GCSE?

If I have got near all full marks in all my courseworks and my school has told me that it gives a 40% boost to my English Language Grade and English Literature grade EACH; what does this actually mean. As in what percentages would I need to achieve in each exam to get a 9 (without the addition of coursework) as I wanted to see the minimum mark that I would need to get to be able to get a grade 9 with my coursework.