Answer:
The vertex is the point 
Step-by-step explanation:
we have

we know ow that
The equation of a vertical parabola into vertex form is equal to

where
(h,k) is the vertex of the parabola
Convert the equation into vertex form
Group terms that contain the same variable, and move the constant to the opposite side of the equation

Factor the leading coefficient

Complete the square. Remember to balance the equation by adding the same constants to each side


Rewrite as perfect squares

therefore
the vertex is the point 
If you are looking for the third angle it is 90 degrees
Answer:
a. Sage and Tom have the same number of talk minutes left on their cell phone plans.
b. y = x - 7
Explanation:
Sage talked for 7 minutes with her dad.
Tom talked for 4 minutes with a friend and 3 more minutes with his mom which means he spoke for :
= 4 + 3
= 7 minutes
They both spoke for 7 minutes and therefore have the same amount of time left.
Algebraic expression:
Assuming the time Tom started with is denoted by x and the time he is left with is denoted by y.
The expression is:
y = x - 7