It's a line in form y = mx.
Two points:
(0, 0) and (1, 4)
The formula of a slope:

Substitute:

Answer: 
Could you please show the question so I can try to answer it
That all cause u the length of the time
Number of days that attracted penalty is from April 5 to July 19 which is 105 days.
Thus the amount of simple interest attracted by Ron is given by: