For this case we have to by definition, if "y" varies directly with "x" it is represented as:
[tex]y = kx[/tex]
Where:
k: It is the constant of proportionality
We have to:
[tex]\frac {1} {4} y = 1.5x[/tex]
We clear the variable "y":
[tex]y = 4 (1.5x)\\y = 6x[/tex]
Thus, the constant of proportionality is: [tex]k = 6[/tex]
Answer:
[tex]k = 6[/tex]
