Okay, just think of dilations as scaling the object bigger or smaller. You are just multiplying all points on the shape by a common scalar.
The only other thing is a negative dilation reflects the shape over the origin (which is quite intuitive cause you negate all the coordinates).
Now for question 1 your just trying to find the scale factor given an original point and a dilated point. Since all points are multiplied by the same factor,
(-3,6)x = (-4,8)
x=4/3
For the second question, just check points to see if all follow the same dilation scale factor. For our purposes it suffices to just check the each vertex.
(1,1) -> (2,2) so the scale factor must be 2
(1,4) -> (2,8) good
(5,1) -> (10,2) good
(5,4) -> (10,8) good
So, this transformation describes a dilation. The scale factor is 2.