Answer: 4/3 or 2/1.5
Explanation:
The constant of proportionality is also known as the slope. This can be found with change in y over change x.
Since we have a graph with distinct points, we can use rise over run. For this graph, we will count 3 units up from (0, 0) and 4 units right to (4, 3). This becomes 4/3 or 2/1.5. This is the constant of proportionality.