y=-1/10x + b
It means you can draw an infinity of lines which are parallel, the difference is their b. b is the value of y when x=0
So you can draw many lines with a slope of -1/10 with b=-1 b=1 b=0 .......
-1/10 means the line goes down from left to right and for each 10 horizontal movement (x), the line goes down of 1 on the vertical (y).