Two ways to do this
You can draw a triangle from (6,10) and (0,8), then count from vertical to horizontal: 2 triangles/6 triangles
The slope is 2/6 or 1/3
You can also use slope formula
First find any two points on graph
(0,8) and (3,9)
Remember: (y2-y1)/(x2-x1) = slope
(9-8)/(3-0) = 1/3
The slope is 1/3