Question

where does the graph of y=-3x-18 intersect the x-axis

Answer 1

 a line crosses the x axis when y = 0 
0 = -3x - 18 

Add 3x to both sides 
3x = -18 

Divide both sides by 3 
x = -6 

Graph intersects x axis at point 
(-6, 0) 

Answer 2

x = - 6 -y/3
I think...