Question 133256
The easiest way to approach a problem like this one is to "mentally" change the problem to {{{x+y = 8}}}

Then you can setup the table or plot the graph. Just keep in mind that when you get ready to draw in the line that is ( x+y =8 ) remember to draw it in as a dotted/dashed line. Then shade the side that makes the original equation valid.

It is not easy to make a table of valid values, since there are an infinite number of y values that make the equation true for any given value of x.