How to use a variable as a divisor in PuLP

Question

I was trying to resolve a LP problem with a constraint that is calculated by dividing variable A by variable B.

The simple version of the problem is as below:

Answer 1

Linear Programming doesn't understand divisions, hence the error :) You have to reformulate it so that the division is formulated linearly. In this case:

prob += x / (x + y) > 0.5  
prob += y / (x + y) < 0.4

is equivalent to:

prob += x > 0.5 * (x + y)
prob += y < 0.4 * (x + y)

Which are linear constraints. Good luck!