Question 104802
Use the point-slope formula y-ysub1= slope(x-xsub1)

Given point (0, 4), use xsub1 = 0 and ysub1 = 4, 

y-4 = -2(x-0)  => y = -2x + 4.  The y-intercept gives you one point on the line, the slope gives you the directions to find another point on the line (start at y=4, go down 2 and then to the right 1 to get the next point on the line).  Or now that you have the equation, find the x-intercept by making y =0 and solving for x.