Graph x = 2y, which is the same thing as y = (1/2)x

It's x <= 2y, so you want a solid line instead of a dotted line

Okay. You've got a graph with a dotted line y = (1/2)x

Let's pick a point. It doesn't matter what point, as long as the point isn't on the line itself. Let's say out point is (5,5).

Plug that point into x <= 2y and see if it works

5 <= 2(5)

5 <= 10

That's true (5 is less than or equal to 10). See how the line y = (1/2)x splits the graph into two parts? We want to shade in the part of the graph that includes the point (5,5).

That should be it. You should have something like this ( https://www.google.com/?gws_rd=ssl#safe=on&q=plot+y+%3D+(1%2F2)x ) with the part above the blue line shaded.