Question 206274
slope m is rise / run or difference in y / difference in x
m = (  (2r-3) - (r-1)  )    /    (  (r+1) - r  )
    = ( 2r - 3 - r + 1 )    /    (r + 1 - r)
    = (r-2) / 1 = r-2

In other words, whatever number r is, the slope is 2 less than that.