ANSWER
Brayden should have expanded the parenthesis first.
EXPLANATION
The expression Brayden is trying to simplify is

To simplify this expression, the first thing to do is to expand the perfect square to obtain:

We can now distribute the negative to the terms in the parenthesis.

Answer:
25%
Step-by-step explanation:
In order to find the chance/probability that Katy wins we need to first find the probability of her winning a single coin toss and then multiply it twice. This is because Katy has 1 win already and needs two more win the entire game. Since a coin toss only has 2 options and only 1 of those outcomes will cause Katy to win, then this means that the probability of Katy winning is 1/2 or 50%. Now we can multiply this probability twice to get the probability of Katy winning the entire game
1/2 * 1/2 = 1/4 or 25%
I believe the answer is -13