So i guess its safe to say im going to have to use a self leveling compound to fill in that low spot? I will see what lowes has tommorow.

The framing square is on the flat side


obviously the slope starts at the seam, but the with the flat edge it goes from the framing square to the pencil




and the whole picture

For those newbs like me who were wondering what i did.... I started prepping to lay some self leveling underlayment.. but kept thinking it wouldnt work and was alot of work. So i kept reading this site, and decided to rent a floor edger. Best damn thing i ever did. It took that slope down in about 20 minutes. I actually decided to skim the whole floor once just to see what it looks like under the thin layer of paint that was on there.. good thing i did. I found hidden, staples, nails, screws.
Ive got to do the whole upstairs. I am finished prepping the master bedroom and master closet, but i wont do another room with out this edger.. man it saves so much time.. Screw belt sanders.