*** jak obliczyc wzrost GROUND RENT?

Czy ktokolwiek wie jak z leasehold obliczyc o ile wzrosnie ground rent

leasehold formula for ground rent increase:

R x A/B

R = the rent payable for the first rent period

A = the most recently published figure for all items index of the RPI

B= the index figure last published at the base date

nigdzie nie mozna tych wartosci A i B znalesc

IS anyone able to work out what my ground rent increase would be like today

£150 x A/B ?

thanks