I have a sewer map with sewer lines connected to manholes. Each manhole has a manhole number and invert elevation. Is there a way to calculate the slope of the sewer lines by the connecting manhole invert elevations? I have tried quite a few different things but haven't been able to make it work. I tried doing a spatial join but it will only join the data to the line from 1 manhole instead of both connecting manholes. Can someone help me out with this please?