The two points we are given will tell us the slope of the line, and the first point even tells us the y intercept.
slope = (y2 - y1) / (x2 - x1) = (1 - 4) / (1 - 0) = -3/1 = -3
Since the function goes through (0,4), our y intercept is 4.
Now we can fill in our function:
y = _ x + _
y = -3x + 4
