Help my program gives me error:argument not optional

Private Sub Command1_Click()
Dim First_Number As Integer
Dim Second_Number As Integer
Dim Answer As Integer
first = Val(txtFirst_Number.Text)
second = Val(txtSecond_Number.Text)

Answer = First_Number + Second_Number

MsgBox ("The total is " & Answer)

first = Val(txtFirst_Number.Text)
second = Val(txtSecond_Number.Text)

where did you declare these variables ?

so the replace the code with the following :-

First_Number = Val(txtFirst_Number.Text)
Second_Number = Val(txtSecond_Number.Text)

this will solve the problem