You are right!
Based on average size of 1,745 sf, the current built-up is 1,745 sf x 124 units = 216,380 sf.
Compared to their plot area of approximately 175,029 sf, the existing built-up ratio is 1.236.
Which means their compensated psf is actually (1.4 / 1.236) x $700 = $790 psf.
Multiply this by 1,745 sf, the average compensation per unit is $1.38 million, which is almost the same as the current individual unit market price!
Multiply by 124 units = $170 million (which is $210 million subtract $40 million development charge + differential premium).
What's going on?
Could the $210 million be "exclusive" rather than "inclusive" of the $40 million development charge and differential premium?
Otherwise really a meaningless en bloc.
