Answer:
-1
Explanation:
:)
1) write slope formula:
rise y2-y1
m= ------- =-----------
run x2-x1
put your problem in the y and x your problem
1 - 2 -1
m=---------= -----------=-1
2 - 1 1
Also you don't even need need to do this entire you can just see what it is decreasing or increasing by it it is a whole number