Option Explicit
Sub test()
Dim impot As Double, revenu As Double
revenu = InputBox("Revenu ?")
If revenu <= 100 Then impot = revenu * 0.1
If revenu > 100 And revenu <= 500 Then impot = 10 + (revenu - 100) * 0.3
If revenu > 500 Then impot = 130 + (revenu - 500) * 0.5
MsgBox impot
End Sub