Analytical fit and parameter extraction and ODE

Hi,

I have a plot of x,y. I know the function f'(x,y) e.g. dy/dx = A.(B-x).exp(-Cx/D) + E.x I also know a relationship between the constants D = A.B/(A+EexpC)

As an input I have a plot of y vs x. How do I obtain

• a good fit to my plot ?
• Values of Parameters: A,B and C corresponding to the best fit ?