slope = -1
Slope formula: y2-y1/x2-x1
the two points are (-1,2) & (2,-1)
Now, fill in the formula and solve!
y2-y1/x2-x1 ---> -1-2/2- -1
Simplify
-1-2/2- -1
-3/3
-1
And there you have it! The slope is -1.
Hope this helps!
Let me know if you have any more questions that need answering :)