Inheritance Tax

I have a question on the NRB when calculating the life time tax and Death Tax, is the do we use the same NRB (325,000) for both instances, or life time tax and death each have a 325,000 to utilise? i came across and an example in the BPP text book where they made it seem as if the latter is true.

The following was the question

Mr Fowler made the following gifts during his lifetime:
£
3 March 2016 Gift to nephew 40,000
14 October 2020 Gift to granddaughter on her marriage 158,000
23 November 2021 Gift to son 210,000

He died on 13 September 2023.

Required
Calculate the IHT payable and state by whom it is payable.