"In the form, I have three textboxes: txtCost, txtRate, txtSale.The following two boxes are filled by a user:txtCost contain the Cost of an item (numbers)txtRate contain the % Rate (3 character), i.e. the txtRate can contain only A,B,C,D,E,F,G,H,I and J. The corresponding value is 1,2,....9,0 respsctively.If a user enters any numbners or characters other than A,B,..J, a msgbox should popup with a e" . . . .