Use the equation (x2-x1)/(y2-y1)
Substitute the value of x and y
The number of ways to arrange the 5 writings in a row is 5! = 5 * 4 * 3 * 2 * 1 = 120 ways.
There is only 1 way to arrange the writings from oldest to newest.
Therefore, the probability is 1/120.
