Написать процедуру нахождения суммы большего и меньшего из трех чисел

Public Class Form1
    Dim x, y, z, Rez As Double
    Public Sub Summ(ByVal x As Double, ByVal y As Double, ByVal z As Double)
        Dim max, min As Double
        max = (x + y + Math.Abs(x - y)) / 2
        min = (x + y - Math.Abs(x - y)) / 2
        max = (max + z + Math.Abs(max - z)) / 2
        min = (min + z - Math.Abs(min - z)) / 2
        Rez = max + min
    End Sub
 
    Private Sub Button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button3.Click
        Close()
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        x = Val(TextBox1.Text)
        y = Val(TextBox2.Text)
        z = Val(TextBox3.Text)
        Summ(x, y, z)
        Label5.Visible = True
        Label6.Text = CDbl(Rez)
    End Sub
 
    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
        TextBox1.Text = "0"
        TextBox2.Text = "0"
        TextBox3.Text = "0"
        Label5.Visible = False
        Label6.Text = ""
    End Sub
 
    Private Sub Label1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Label1.Click
 
    End Sub

Dim max = Math.Max(Math.Max(x, y), z)
Dim min = Math.Min(Math.Min(x, y), z)
Dim sum = max + min