Answer:
from 0 to 12 hours, that is 
Step-by-step explanation:
Notice that the x represents the number of phone hours used, therefore it has to be a number larger or equal zero, but NOT a negative number.
So on one end we have that the number of phone hours used (x) must be larger or equal zero: 
On the other hand, when the battery goes to zero, there are no more phone hours to use. We can find what is that other limit by making the battery percent (y variable) equal to zero, and solve the equation for x, thus giving us the upper limit of usable phone hours:

Therefore, the upper limit for the number of usable phone hours is 12 hours.
Then we write:
hours
Y =

This is because 16 needs to be added to the base amount since the teachers cost is automatically added in.
Answer:
x - 3
Step-by-step explanation:
Given

Note that x² - 9 is a difference of squares and factors as
x² - 9 = (x + 3)(x - 3), thus
Cancel the x+ 3 factor on the numerator/ denominator leaving
x - 3 ← in simplified form
Explanation:
The N stands for Pi so when you type in the answers to Khan Academy use the Pi symbol when theres an N! These are the common questions and common radius Khan Academy gives when they ask to find the radius of the circle.
Answers:
For 4 - 267.95
For 1/4 - 1/48n
For 1 - 4/3n
For 9 - 972n
For 7 - 1372/3n
For 6 - 288n
For 3 - 36n
For 10 - 4000/3n
For 8 - 2048/3n
For 1/2 - 1/6n
For 5 - 500/3n
For 2 - 33.49
Step-by-step explanation:
<u><em>I did the go math so all of these rights and the majority of the answers are the questions Khan Academy will ask you to find the radius of the circle.</em></u>