ANSWER
13.5
EXPLANATION
It was given that, y varies directly as x.
Therefore, the variation equation is of the form:
[tex]y = kx[/tex]
If y is 4.5 when x is 3, then we can substitute to find the constant of variation.
[tex]4.5 = 3k[/tex]
Divide both sides by 3;
[tex]k = \frac{4.5}{3} [/tex]
[tex]k = \frac{3}{2} [/tex]
Hence the equation becomes:
[tex]y = \frac{3}{2} x[/tex]
When x=9,
[tex]y = \frac{3}{2} \times 9 = 13.5[/tex]
