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Work Shown:
Let's apply the slope formula to get...
m = (y2 - y1)/(x2 - x1)
m = (-13 - 10)/(10 - (-13))
m = (-13 - 10)/(10 + 13)
m = -23/23
m = -1
The slope is -1
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Extra info:
The slope is the rate of change. Specifically it's the change in y over the change in x. So that's why we divide the (y2-y1) over the (x2-x1). The (y2-y1) is the change in y; the (x2-x1) is the change in x.
You can think of it as
slope = rise/run
rise = y2-y1 = change in y
run = x2-x1 = change in x
