Convert byte to negative value and vice versa in VB

Question

Dim A As String = String.Join("", "1F", "40")
Dim B As Integer = Convert.TonInt32(A,16) 

return 8000.

My Questions

1. How to convert into hex in VB if my decimal value is in negative (i.e. -8000 or -80 as for example)?
2. How to convert into negative value in VB if a hex value of EE6C

Thank you for your help.