Answer:
Option (D) is correct
Step-by-step explanation:
If y is a multiple of x and versa, it will have a constant of proportionality.
Option (A)
y = (81/3)xy
y will cancel out
1=27x
It is not correct
Option (B)
y=9xy
y will cancel out
1=9x
Option (C)
y=3xy
y will cancel out
1=3x
Option (D)
y = (1/9) x
y will cancel out
x=9y
In option (D), we see that x is 9 times of x. It means it has constant of proportionality equal to 9.