#1
order pairs
(5,4), (10,8), (15,12)
#2
you need to use the order pairs from #1 to graph on the grid and draw a line connecting from those order pairs.
#3
slope = (8-4)/(10-5)
slope = 4/5
#4
No, if it's a constant rate.
However, you need to pick two points next to each other and on the same line. Slope is rise over run.