Technical question! 802.11ac 5/6 256 QAM

I am trying to figure out how they have calculated the values below:

They have calculated a data rate of 867 Mbit/s for 802.11ac assuming 256 QAM and a rate of 5/6. How would the calculation be affected if the coding rate or modulation method was changed?

I hope there is someone out there who can help comprehend this!

Thanks
Computerdummy

you are asking a calculus question on an arithmetic forum.

you are more likely to get an answer here:

CWNP Forums