Why do you want me a little bit of
ABCDEFGH = 22.
HEFG = 12
ABCD = 10
To find the slope take your points, they should be (x1,y1) (x2,y2), proceed to subtract y2-y1 over x2-x1. after you calculate that simplify and put it in y=mx+B (the slope goes in the m position and x is usually left open)
If the number you are rounding is followed by 5, 6, 7, 8, or 9, round the number up (+1).
If the number you are rounding is followed by 0, 1, 2, 3, or 4, round the number down (no change).