Answer:
10 units
Step-by-step explanation:
Using a corrdinate grid, you can plot the points to find the distance between each one to get your answer. You can also look at the points given:
R(-2, 4) to S(3, 4) = moves in a straight line east (right) for a total of 5 units
S(3, 4) to T (3, -1) = moves in a straing line south (down) for a total of 5 units
5 units + 5 units = 10 total units of walking trail