VBA code simplification - vba

Question

I have the following macro
Private Sub ComboBox1_Change()
If ComboBox1 = "Berlin" Then
Range("C20").Activate
Else
If ComboBox1 = "Paris" Then
Range("C100").Activate
Else
If ComboBox1 = "London" Then
Range("C150").Activate
End If
End If
End If
End Sub
This macro takes the value from a dropdown menu and goes to the cell, where the value is. First question is:
How can I take the values from the cells and not write them specifically in the code?
Second question is:
How can I simplify the procedure and not write for every value an IF?

Answer 1

First, you probably don't actually want to Activate the range! See this answer:
How to avoid using Select in Excel VBA macros
Secondly, your code...
Your Code
Private Sub ComboBox1_Change()
If ComboBox1 = "Berlin" Then
Range("C20").Activate
Else
If ComboBox1 = "Paris" Then
Range("C100").Activate
Else
If ComboBox1 = "London" Then
Range("C150").Activate
End If
End If
End If
End Sub
Using ElseIf
Private Sub ComboBox1_Change()
If ComboBox1 = "Berlin" Then
Range("C20").Activate
ElseIf ComboBox1 = "Paris" Then
Range("C100").Activate
ElseIf ComboBox1 = "London" Then
Range("C150").Activate
End If
End Sub
See documentation: https://msdn.microsoft.com/en-us/library/office/gg251599.aspx
Not hard-coding the values
Private Sub ComboBox1_Change()
Dim rng as Range
Set rng = Nothing
Set rng = ActiveSheet.Range("C:C").Find(ComboBox1.Text)
If Not rng Is Nothing Then
' As I say, you probably don't actually want to use Activate!
rng.Activate
End If
End Sub
See more about the Range object here:
https://msdn.microsoft.com/en-us/library/office/ff838238.aspx
It has useful methods like Address or Value for common use in VBA. The Find function returns a Range object or Nothing if the given value isn't found in the given range.

Answer 2

How can I simplify the procedure and not write for every value an IF?
If you need to test your ComboBox repeatedly (like your If-ElseIf structure), you can use the SELECT CASE to simplify your code:
Private Sub ComboBox1_Change()
Select Case ComboBox1
Case Is = "Berlin"
Range("C20").Activate
Case Is = "Paris"
Range("C100").Activate
Case Is = "London"
Range("C150").Activate
Case Else
Range("C1").Activate
End Select
End Sub
This looks at the value of ComboBox1 and picks the appropriate section to run. For example, if ComboBox1 = "Paris", it skips to the "Paris" case and only runs that section (Range("C100").Activate).
This makes it much easier to add more items to your options, and it reduces the clutter of lots of If-ElseIf-Else lines.
Edit: As mentioned by Wujaszkun, adding the Case Else section handles a ComboBox1 value that was not one of the specified cases.