I weight 135lbs I do 4mi per day on treadmill. how many pounds approx am i going to lose in a week? thanks.?

None if you do that treadmill every day. The body gets used to that very same exercise and the metabolism goes down into saver mode. If you want to lose weight it would be best if you alternate another exercise with the treadmill---for instance, i do the elliptical trainer and I do alternate with the hoola hoop. I do 2 days on the elliptical, 1 day hoola hoop, 1 day elliptical, 2 days hoola hoop and so forth. That way my metabolism won't go into saver mode...and the scale told me that I am doing the right thing....