Can such an expression be equated to a conditional system in linear programming? How to transform or put him in conditional system?

I want to create a theoretical biogas production equation. It is necessary to calculate how much to enter the specific raw materials. I am thinking of using one of the methods of solving the optimization problem - linear programming.

Objective function:

Subject to:

Can such an expression be equated to a conditional expression (subject to) in linear programming. How to transform or put him in a conditional equation?

[Rik]

Have a read here and here. It will greatly improve your chances of getting an answer.

Keep in mind that you know all the context and we don't.

[John D'Errico]

What is conditional here? Note that the second of those equalities listed is not even linear, but you can transform it to be so, by multiplying by the denominator.