Slope-intercept equation from graph (messiah decrypter part I)

https://www.khanacademy.org/math/algebra-home/alg-linear-eq-func/alg-writing-slope-intercept-equations/e/slope-intercept-equation-from-graph

Slope-intercept equation from graph

Problem

Find the equation of the line.
Use exact numbers.

$y=$y, equals 

$x+$x, plus 

$\small{1}$$\small{2}$$\small{3}$$\small{4}$$\small{5}$$\small{6}$$\small{7}$$\small{8}$$\small{9}$$\small{\llap{-}2}$$\small{\llap{-}3}$$\small{\llap{-}4}$$\small{\llap{-}5}$$\small{\llap{-}6}$$\small{\llap{-}7}$$\small{\llap{-}8}$$\small{\llap{-}9}$$\small{1}$$\small{2}$$\small{3}$$\small{4}$$\small{5}$$\small{6}$$\small{7}$$\small{8}$$\small{9}$$\small{\llap{-}2}$$\small{\llap{-}3}$$\small{\llap{-}4}$$\small{\llap{-}5}$$\small{\llap{-}6}$$\small{\llap{-}7}$$\small{\llap{-}8}$$\small{\llap{-}9}$$y$$x$

Stuck?