What is the slope for the following set of data?

Question

x 2 4 6 8

y 1 -2 -5 -8

Answer 1

Did you notice for each increase of 2 in the x's , there is a decrease of 3 in the y's

so quick way:
slope = -3/2

Answer 2

x-change: +2
y-change: -3

slope: -3/2