This is quite simple, all you have to do is include an equality constraint like this

Max = 3*x1+5*x2

x1

It's called an accounting row. It is an equation that simply adds things up.

x1 + x2 - Y = 0

Later, these things that are added up can also be constrained.

Y < 100

or

Y > 10

Hey guys,

thanks for your answers !

I found the answer in the lingo manual.

The solve() function will do the job, refer to the following:

Model:

Max = 3*x1+5*x2

x1