There are 12 possible outcomes, 6 for the die for each of the 2 for the coin. Only one comprises a 5 and a tail so the probability, assuming a fair coin and die, is 1/12.
If you graph the points on a graph, you can see that in order to reach the next point, you go down two boxes, and over one box. This makes the slope -2 by using rise over run.
