Change the naming convention of the variables to reflect a Double data type (e.g. Private _dblLength As Double).

Public Class frmFence

Private Sub totalBtn_Click(sender As Object, e As EventArgs) Handles btnTotal.Click

Dim len As Double = 0

Dim wid As Double = 0

Dim lCost As Double = 0

Dim perimeter As Double = 0

Double.TryParse(txtLength.Text, len)

Double.TryParse(txtWidth.Text, wid)

Double.TryParse(txtLCost.Text, lCost)

'Dim houseArea As My.Resources.Rectangle = New My.Resources.Rectangle()

Dim house As Rectangle = New Rectangle(len, wid)

perimeter = house.GetPerimeter()

lblTotalCost.Text = (perimeter * lCost).ToString("C2")

End Sub

Private Sub exitBtn_Click(sender As Object, e As EventArgs) Handles btnExit.Click

Me.Close()

End Sub

End Cl