how to calculate market value using cost method?

transaction price - building cost ( total build up )  = land value

land value / land area = land value persf

example :
transaction price = RM 1,000,000
building up area = 2,000 sf
land area = 3,500sf
price per sf = RM 100

question
a) building cost ( build up x price per sf )
b) land value ( transaction price - building cost )
c) land value per sf ( land value / land area )

answer
a) RM 100 x 2,000 = RM 200,000
b) RM 1,000,000 - RM 200,000 = RM 800,000
c) RM 800,000 / 3,500 = RM 229 persf