Answer:
The annual passenger revenue of the rail transport corporation was $930 million when:
R = 930
-20|t-15| + 1,010 = 930
-20|t-15| = 80
|t-15| = 4
So, we can see that t-15 = 4 and t-15 = -4 both lead to an annual revenue of $930 million dollars.
To find the values of t, we add 15 to both sides of the equation:
t-15 = 4 => t = 19
t-15 = -4 => t = 11
So, the years where the passenger revenue was $930 million are:
2011
2019