Answer
Please see the graph, made using graphing software.
Work Step by Step
$y <3x$
Change the inequality sign in $y <3x$ to an equal sign ($y =3x$) so we can draw the boundary line.
Let $x=0$
$y =3x$
$y=3*0$
$y=0$
Let $x=2$
$y=3x$
$y=3*2$
$y=6$
$(0,0)$ and $(2,6)$ are on the line.
Since $(0,0)$ is on the line, we can't use this point to determine what side of the line to shade.
$(2,2)$ is our test point.
$y <3x$
$2 <3*2$
$2 < 6$ is a true statement, so we shade the side of the line with the point $(2,2)$.