Answer: 2.5
Step-by-step explanation:
We know that the constant of proportionality is the ratio between two directly proportional quantities.
The equation of direct variation between two quantities x and y is given by :-
[tex]y=kx[/tex], where k is the constant of proportionality,
The given equation : - [tex]y =2.5xy[/tex]
When we compare to the general direct variation equation , we get
[tex]k=2.5[/tex]
hence, the constant of proportionality in the equation 2.5
