In the following table, do x and y vary directly:

x	y
3	4.5
5	7.5
8	12
11	16.5

$\dfrac{x$1}{y1} = \dfrac{3}{4.5} = \dfrac{2}{3},\\[1em] \dfrac{x2}{y2} = \dfrac{5}{7.5} = \dfrac{2}{3},\\[1em] \dfrac{x3}{y3} = \dfrac{8}{12} = \dfrac{2}{3},\\[1em] \dfrac{x4}{y4} = \dfrac{11}{16.5} = \dfrac{2}{3},\\[1em]

$\Rightarrow \dfrac{x$1}{y1} = \dfrac{x2}{y2} = \dfrac{x3}{y3} = \dfrac{x4}{y4} = a constant

Hence, x and y are in direct variation.