Let : X=ln(x) ; Y=ln(y) ; c=exp(b)
Y = b+a*X
It is a linear regression !
I believe that a variable y is related to x in the following way
I only have 3 data points for x and y, how can I find the best values of a and c to fit the data? Either a method or some free software for regression would be good, I like to know how to do it manually though