what is the slope of the line that contains the points (-2,5) and (6,-3)?

Slope.....

Subtract the y coordinates in some order    -3 - 5  = -8      (1)

Subtract the x coordinates in the same order  6 - -2   = 8    (2)

Slope  =  (1) /(2)    =   -8 / 8    =   -1