Solve a cell by changing another cell using Solver in VBA

CallSolver.vba

'' First, you have to open the Visual Basic for Applications editor
'' Tools > References > Check "Solver" (near the top)

'' Setup here: http://imgur.com/UZPmZQQ

Sub MyMacro()

'' x is going to store your target value, which currently sits in cell C5
    Dim x As Integer
    x = Range("$C$5").Value
    
'' If you're on a different Excel, this might all be ".xla" instead of ".xlam"

'' You gotta make sure Solver is reset. 
    Application.Run "Solver.xlam!SolverReset"

'' Run solver's "SolverOk" function. This takes:
'' SovlerOk([SetCell], [MaxMinVal], [ValueOf], [ByChange], [Engine], [EngineDesc])
'' [SetCell] - target cell which you're solving for. In this case, C4.
'' [MaxMinVal] - 1=Max, 2=Min, 3=Set to a value. Typically, use 3.
'' [ValueOf] - target value of [SetCell]. In this case, we're using x
'' [ByChage] - which cell changes their value. In this case, C3
'' [Engine] - no idea
'' [EngineDesc] - still no idea
    Application.Run "Solver.xlam!SolverOk", "$C$4", 3, x, "$C$3", 1, "GRG Nonlinear"
    
'' This variable will store the result type. Stolen from http://peltiertech.com/Excel/SolverVBA.html
    ' Result = 0, Solution found, optimality and constraints satisfied
    ' Result = 1, Converged, constraints satisfied
    ' Result = 2, Cannot improve, constraints satisfied
    ' Result = 3, Stopped at maximum iterations
    ' Result = 4, Solver did not converge
    ' Result = 5, No feasible solution
    
    Result = Application.Run("Solver.xlam!SolverSolve", True)
    Application.Run "Solver.xlam!SolverFinish"
    
End Sub