Explanation:
the slope of a line is the ratio "y coordinate change / x coordinate change" when going from one point on the line to another.
in other words : how much does y change, when x changes a certain amount ?
so let's pick 2 points in the list.
I go for the easiest (0, 0) and then (1, 3).
x changes by +1 (from 0 to 1).
y changes by +3 (from 0 to 3).
so, the slope is +3/+1 = 3
graphing it is easy. just mark the points of the list on the coordinate grid and then draw the line through the points.
x is the horizontal direction (left/ right coordinate axis), y is the vertical direction (up/down coordinate axis).
so, mark at least the points (0, 0), which is the center (or origin) of the coordinate lines, and (2, 6), and draw a line through both points. the line should extend beyond the marked points.