Delete rows missing contents in AF then A

Good day to you. here is what I am working on. If a row in Column AF does not say “Cust” than I want to delete it, next if a row in Column A does not say “Numb” I want to delete it. Here is what I am working with so far. If you can assist, thank you.

Sub Delete()

FirstRow = 2
LastRow = Range("AF" & Rows.Count).End(xlUp).Row
For R = LastRow To FirstRow Step -1
If Range("AF" & R).Value = "Cust" Then
after Cust
Rows(R).Delete
End If
Next
End Sub