For this case we have the following equation:

Let 
We have:

By definition, given an equation of the form 
The quadratic formula, to find the solution can be written as:

In this case we have:

Substituting in the quadratic formula we have:
See attached image
Answer:
Option B
Answer:
D. 
Step-by-step explanation:
let's call A the number of copies sold of newspaper A and B the number of copies sold of newspaper B.
So, we can formulate the following equations from the sentence: a certain store sold copies of 256 Newspaper A for $1.00 each and copies of Newspaper B for $1.25 each as:
A + B = 256 (1)
1A + 1.25 B = Total Revenue (2)
Then, r and p are equal to:
(3)
(4)
Isolating A from (4) and B from (1), we get:
(5)
(6)
Finally, replacing (5) and (6) in (3), we get:

Answer:
120 deg
Step-by-step explanation:
Answer: x=14
Explanation: the angle needs to equal the other angle, which is 63. To figure this out, we subtract 21 from 63. We get 42. 42 divided by 3 is 14. We are basically doing the equation in reverse.