revving issues 5 speed standard on 2000 Volkswagen Golf

when I drive on the high way at in 5th gear I tac will read 3000rpm around 80 kmph and at 120 kmph the tac reads 4000rpm does anyone have any ideas this happens all the time does not matter if the motor is cold or warm

Asked by for the 2000 Volkswagen Golf
Sounds like the clutch is slipping.