Hello, actually mentioned the previous parts as well. I have to define a binary variable and write new equations. I know it in theory, but I can’t put it into practice.

The equation I want to formulate is as follows: if d(i) - e(i) = 0, then x(i) >= 0 e(i) and x(i) are positive variable…

How do I define the condition d(i) - e(i) = 0 for a binary variable? How should my entire description be? Please can you help me?