Example of constructing a model with OpenSolver API

SimpleLP.bas

Option Explicit

Function Test()
    Dim Sheet as Worksheet
    Set Sheet = ThisWorkbook.Sheets("Sheet1")
    
    OpenSolver.ResetModel Sheet
    OpenSolver.SetDecisionVariables Sheet.Range("D4:F4"), Sheet
    OpenSolver.SetObjectiveFunctionCell Sheet.Range("H6"), Sheet
    OpenSolver.AddConstraint Sheet.Range("H8:H9"), RelationLE, Sheet.Range("J8:J9"), sheet:=Sheet
    OpenSolver.AddConstraint Sheet.Range("H10"), RelationGE, Sheet.Range("J10"), sheet:=Sheet
    OpenSolver.AddConstraint Sheet.Range("H11"), RelationEQ, Sheet.Range("J11"), sheet:=Sheet
    
    OpenSolver.RunOpenSolver sheet:=Sheet
End Function