Verify 100/ 1 + 2 ^ (-log base2 (x/100-x) is X

100 / (1 + 2^(-log₂(x/(100-x))))
= 100 / (1 + 1/(2^(log₂(x/(100-x)))))
= 100 / (1 + 1/(x/(100-x)))
= 100 / (1 + (100-x)/x)
= 100x / (x(1 + (100-x)/x))
= 100x / (x + 100 - x)
= 100x / 100
= x.