新手在线求解加减乘除算法

Private Sub Command1_Click()

Let a = Text1.Text
Let b = Text2.Text
Let c = Text3.Text
Let d = Text4.Text
Let e = Text5.Text
Let f = [ Val(d) - ( Val(a) * Val(e) / Val(b) ) ] / Val(c)
Text6.Text = f

End Sub
 本人刚学，请问这句有什么问题啊？