What is the slope of (1,3) and (2,1)

Ax+b=y

put the both values the left one is x and the right one is y

(1,3) = > a+b=3

(2,1) = > 2a+b=1

subtract both of the equations you will get - a=2

so a=-2 and put a in any of the equation you will get b is 5 so the equation is - 2x+5=y

the slope is the x's number so it's - 2