Word Problem 4 - Horses in the field

There are 33 horses in a field. 15 horses go into the barn. Then 7 of them come back out. How many horses are standing in the field?
Write a program in Visual Basic to find out how many horses are standing in the field.

 Public Class Form1  
   Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click  
     'Declare variables  
     Dim I, O, B, horses As Integer  
     'Set values  
     O = 33  
     I = 15  
     B = 7  
     horses = O - I + B  
     'Display results  
     MessageBox.Show("There are " & horses & " horses in the field.")  
   End Sub  
 End Class