(where C= -Ak and e is the natural logarithm) and, first, I wanted to know if anyone is familiar with this particular model.

Second, I have been trying to solve for the unknowns A, B, and C by plugging in three points on a graph that I have, thusly:

16.4 = A/1+Be^(2C), 16.8 = A/1+Be^(10C), and 21.6 = A/1+Be^(19C)

I decided to set up a system of equations and solve for each variable one at a time, so first I isolated A in the first two equations:

A = 16.4 + 16.4Be^(2C)

A = 16.8 + 16.8Be^(10C)

and set them equal: 16.4 + 16.4Be^(2C) = 16.8 + 16.8Be^(10C)

From this point, I ran into a snag because I wasn't sure how I wanted to bring the exponents down without eliminating B entirely. I thought about simplyifying by dividing by B so that I have 16.4e^(2C) = .4/B + 16.8e^(10C), but I'm not sure that helps.