Answer:
(C)9/2
Explanation:
Given the equation

Two variables are in direct proportion when it is written in the form y=kx where k is the proportionality constant. To obtain the constant of proportionality, we simply make y the subject of the equation.
Therefore, we cross multiply.
2y=9x
Divide both sides by 2

Therefore, the constant of proportionality in the equation is 9/2.