Hola, podes guardar los numeros en un vector y ordenarlos..pero proba esto:
Código:
Private Sub Command1_Click()
Dim a As Integer, b As Integer, c As Integer
a = 1
b = 5
c = 10
MsgBox (a + b + c * 2 + Abs(a - b) + Abs(a + b - c * 2 + Abs(a - b))) / 4
End Sub
saludos.