Answer:
The ratio of how much they have watched to how much they have left to see is 4 : 1.
Step-by-step explanation:
Consider that the total duration of the film is, 1.
It is provided that James and Cameron paused when there is one-fifth left to watch.
That is, they have already watched, 
th of the film.
Compute the ratio of how much they have watched to how much they have left to see as follows:
Thus, the ratio of how much they have watched to how much they have left to see is 4 : 1.
According to the question,
Let,
"n" represent the number of miles semir walked.
"y" represent the number of miles sarah walked.
Now, according to the question,
y = 2n - 5 ........................this is your equation
Also,
the question states, each of them collect $18 in pledges for every miles walked.
Given,
Sarah collected $450
Now,
Using unitary method,
Sarah collects $18 for 1 mile
Sarah collects $1 for (1 / $18) mile
Sarah collects $450 for (1 / 18) * 450 mile
= 25 miles
So, Sarah walks 25 miles.
Now,
Taking equation,
y = 2n - 5
Since, y is the no. of miles sarah walked, we can write 25 in place of "y" So,
(25) = 2n - 5
25 + 5 = 2n
30 = 2n
30 / 2 = n
15 = n
Since, "n" is the no. of miles that semir walked, Semir walked 15 miles.
