VB .Net - Programa Carros

Criei a classe carros

Public Class carros

    Private _combustivel As Double

    Private _km As Double

    Public Property combustivel() As Double

        Get

            Return _combustivel

        End Get

        Set(ByVal value As Double)

            _combustivel = value

        End Set

    End Property

    Public Property km() As Double

        Get

            Return _km

        End Get

        Set(ByVal value As Double)

            _km = value

        End Set

    End Property

    Public Sub abastecer(ByVal L As Double)

        If (combustivel() + L) > 50 Then

            MsgBox("Não é possível abastecer")

        Else

            combustivel() = combustivel + L

            MsgBox("abastecimento ok")

        End If

    End Sub

    Public Sub move(ByVal distancia As Double)

        Dim litros_necessarios As Double

        litros_necessarios = distancia / 15

        If (combustivel() < litros_necessarios) Then

            MsgBox("Impossível mover esta distância, combustível insuficiente.")

        Else

            km() = km() + distancia

            combustivel() = combustivel() - litros_necessarios

            MsgBox("Movimento ok")

        End If

    End Sub

End Class

Aqui é o programa principal

Public Class Form1

    Dim c As New carros

    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        atualiza()

    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        c.abastecer(TextBox1.Text)

        atualiza()

    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

        c.move(TextBox2.Text)

        atualiza()

    End Sub

    Public Sub atualiza()

        TextBox4.Text = c.combustivel

        TextBox3.Text = c.km

    End Sub

End Class

Pegue o projeto neste link: http://www.mediafire.com/?k72av1ld0t7199g

Espero ter ajudado, até mais... Abraços!