Answer:
12 units
Step-by-step explanation:
The first segment, RS, is along the grid line y=4 from x=-1 to x=5, a total distance of 5-(-1)=6 grid units.
The second segment, ST, is along the grid line x=5 from y=4 to y=-2, a total distance of 4-(-2)=6 grid units.
The total length of the trail is the sum of the lengths of the first and second segments, so is 6+6=12 units.
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It can help to plot the points on a graph so you can better see what it is you're being asked to find.
