Answer
The constant of proportionality = 2 trees cut down per day spent on the island.
Step-by-step explanation
The total number of trees he cut down is y
The number of days Harry is stranded on the island is x
The fact that these two quantities are directly proportional to each other is represented as
y ∝ x
If we introduce the constant of proportionality, we will write it as
y = kx
To now obtain the constant of proportionality, we will use the graph of the relationship between x and y. The costant of proportionality is the same as the slope of the graph
For a straight line, the slope of the line can be obtained when the coordinates of two points on the line are known. If the coordinates are (x₁, y₁) and (x₂, y₂), the slope is given as

For this question, the two points are
(x₁, y₁) and (x₂, y₂) are (0, 0) and (2, 4)

Hope this Helps!!!