Question

Y and x have proportional relationship and y=9 when x=2 what is the value of y when x=3 ??????

Answer 1

Y = 9       x = 2
y = ?       x = 3

You can either cross multiply and you'll get 13.5
OR you can divide 2 BY 9 and you'll get 4.5 so you multiply 4.5 with 3 and you'll still get 13.5.
So both ways you'll get 13.5.

Answer 2

I assume you mean a direct proportion  y = kx where k is a constant
y = 9 when x == 2 so  9 = 2k  giving k = 4.5

So when x = 3,  y = 4.5x = 4.5*3 = 13.5 answer