Respuesta :

upandover

Slope-Intercept Form: y = mx + b

m = slope

b = y-intercept

3x + y = 21

3x - 3x + y = 21 - 3x

y = -3x + 21

Answer: y = -3x + 21

Hope this helps!! :)
Slope intercept form y=mx+c
y=-3x+21