If we know the root Demos means people and graphic means picture, let's put the english terms together.
Demo graphic
People graphic
So this is going to be a "People Graphic." So we know that Countries and Continents are ruled out.
Now I just used logic to figure out whether it's population or leaders. A map showing the leaders of something would be useless, but a map showing population is useful. So I assumed that a Demographic map shows population (I also looked it up to check, and yes this is right.)
Standard form: Ax+By=C first put in slope-intercept form: slope = (0+5)/(6-3) = 5/3 pick point D: 0 = 5/3(6)+b -> b= -10 slope-intercept form: y=(5/3)x-10 multiply both sides by 3: 3y=5x-30 put in standard form: 5x-3y=30