Respuesta :

y= mx + b

y= 9x+b

(-9,1)—> (x,y) —> x=-9 and y=1
With that information we can find b by pulling in the variables we know of which are x and y

1=9(-9) + b
1= -81 + b. (You want to have b alone)

82 =b

y= 9x + 82