We are told that Jed is standing behind Amy.

Let x = number of people behind Jed
Let y = number of people ahead of Jed but behind Amy
Let z = number of people ahead of Amy


So, our diagram looks like this: BACK|-----x people----JED------y people------AMY----z people------|FRONT

Amy and Jed are among 35 people
We can write: x + y + z + Jed + Amy = 35 people
In other words, x + y + z + 2 = 35
Simplify: x + y + z = 33

The number of people in front of Amy plus the number of people behind Jed is 24.
We can write: x + z = 24

There are 15 people behind Amy, including Jed
x + y + Jed = 15
In other words: x + y + 1 = 15
Or: x + y = 14

Take:
x + y + z = 33
x + z = 24

Subtract the bottom equation from the top equation to get: y = 9

Take: x + y = 14
Since y = 9, we know that x = 5

Take: x + y + z = 33
Since y = 9 and x = 5, we know that z = 19

We have: BACK|-----5 people----JED------9 people------AMY----19 people people------|FRONT

How many people are in front of Jed?
The number of people in front of Jed = y + AMY + z
= 9 + AMY + 19
= 29

Answer: D

Cheers,
Brent