Question

Graph y is less than or equal to 3

Answer 1

It will be a straight solid line, which is horizontal to 3 on the y axis, so no matter what point you chose on the horizontal line y will always equal 3.
If you need to also include shading on your graph the shading will be above the horizontal line

Answer 2

It would be a horizontal line (dotted line) at the y intercept 3. Make a line 3 units up, and it is dotted. Shade below the dotted line, to show the "less than" part. Hope this helps