Answer:
I believe it is 1, I might be wrong.
Explanation:
Two points on the graph are (1,2) and (2,3)
The first set has variables of x1 and x2 the second has variables of y1 and y2.
The formula is y2 - y1/x2 - x1
Put in the values and you get 2 - 3/2-1.
You would get 1/1, which is equivalent to 1.