How to implement SUM operation in Google OR-Tools for C#

Question

I would like to know how can I implement a SUM operation in C# using OR-Tools. In my problem, I have the following constraint:

Constraint

NOTE: My problem is a Linear Programming Problem.

Answer 1

You can use arithmetic operators:

model.Add(4 * r + 2 * p == 56);

or

model.Add(LinearExpr.Sum(new IntVar[] {r, p}) == 20);

See: https://github.com/google/or-tools/blob/master/ortools/sat/doc/integer_arithmetic.md

Answer 2

You can follow the examples in this section:

https://github.com/google/or-tools/blob/master/ortools/sat/doc/integer_arithmetic.md