The constant proportionality is the same thing as SLOPE
Here's a little trick to find slope using a graph like that!
Slope can also be described as RISE (how many units UP it takes to get to the next point) divided by RUN (how many units to the left or right the next point is)
Going from the origin (0,0) to the next point/dot on the graph, it goes UP 10 UNITs and to the RIGHT by 1 UNIT!
10 ÷ 1 = 10
The constant proportionality/slope of the graph is 10!