You can put this solution on YOUR website! -12x + y = 21
y=12x+21
21 is the Y intercept.
Setting Y=0 & solving for x gives us the X intercept.
0=12x+21
12x=-21
x=-21/12
x=-7/4 ans. for the X intercept.
Proof: (graph 300x200 pixels, x from -6 to 5, y from -10 to 25, 12x +21).