I am having hard time with this question. What are the possible dimensions of the Khufu pyramid, based on the information (asking height, side lengths, slant height)

Question

I am having hard time with this question. What are the possible dimensions of the Khufu pyramid, based on the information (asking height, side lengths, slant height) 
" According to this site
115,000-200,000 casing stones were used
The stone blocks usually are larger in the lower layers (1.5m = 3 cubit) and smaller in the upper layers. Most are between 1.5 and 2 cubit large (average of 127 x 127 x 71cm). 1 cubit = 0.524m
Originally probably 210 stone layers, now only 201 layers"
It later gives the answers, but i can only calculate the height of the pyramid and  even that is off .. we need to show work and how we got the answers..

my idea was, 0.71m x210 will be the height, if the stones are put laying down.. it gives 149.1 m that is 284.54  cubits (if we take 1 cubit = 0.524 m) if we use 3 cubits =1.5 m it will be 298.2 .. the answer should be 280. and i stuck right here..