Answer:
The constant of proportionality of the graph is 0.75
Step-by-step explanation:
The coordinates of the points on the lines are;
(400, 300), (250, 187.5), and (120, 90)
Which can be written in a tabular form as follows;
Number of US dollars [tex]{}[/tex] Number of euros
120 [tex]{}[/tex] 90
250 [tex]{}[/tex] 187.5
400 [tex]{}[/tex] 300
Given that the graph is a straight line graph, we can represent the graph with the straight line equation, y = m·x + c
Where;
c = The y-intercept (where the graph meets the y-axis) = 0
m = The slope = The constant of proportionality
[tex]Slope, \, m =\dfrac{y_{2}-y_{1}}{x_{2}-x_{1}}[/tex]
[tex]m =\dfrac{300-90}{400-120} = \dfrac{210}{280} = 0.75[/tex]
We have, y = m·x = 0.75·x.
Therefore, the constant of proportionality of the graph = 0.75.