Atank contains 8000 l of water each day a half of the water in the tank is removed how much water will be in the tank at the end of

You forgot an essential part of the question which is the date as to when you’re supposed to stop counting down. But I’ll give you a few dates to try and be of assistance...
(Day 1) 8000/2=4000
(Day 2) 4000/2=2000
(Day 3) 2000/2=1000
(Day 4) 1000/2=500
(Day 5) 500/2=250

And so forth like that