CombineTwoArrays Function

to add the values in 2 arrays (ranges) D1:G3 and D7:G9

Sub snb5()
[D1:G3].Offset(20) = [index(D1:G3 +D7:G9,)]
End Sub

you can use this UDF

Function snb7(c01 As Range, c02 As Range)
  snb7 = Evaluate("index(" & c01.Address & "+" & c02.Address & ",)")
End Function

You will have to enter this UDF as an arrayformula: ctrl-shift-enter

{=snb7(D1:G3,D7:G9)}
and autofill the adjacent cells correponding to the range's size