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.
The simplest form of an interest equation is A = P(1+rt)
where A = the total amount of money at the end, P = the principal (or amount of money you started with), r = the rate in percent, and t = the time in years.
In this case, P = 15000, r = 0.03 (because 3% in decimal form is 0.03), and t = 1:

So, after 1 year he will get $15450 back, making him $450 more.
Answer:
You are correct. Good job and merry Christmas, have a good day.