The standard form of a line:

We have the equation of a line in the slope-point form:
use distributive property
add 3 to both sides
multiply both sides by 2
subtract x from both sides
change the signs

Answer:
The age of the person who entered the room is 15
Step-by-step explanation:
We are given:
Ages of 5 people in a room are:
17, 16, 15, 17, 22
A person enters room, and then the mean age of 6 people is 17.
We need to find the age of person who entered the room.
The formula to calculate mean is: 
Now, in question we are given mean of 6 people that is 17
The age of 5 people are given while age of one person who enters the room is unknown.
Let age of person whose age is unknown= x
Now finding x using mean formula

So, The value of x: x=15
Hence, the age of the person who entered the room is 15
D. If you ask the amount of projects completed using the computer lab you are asking a statistical question. Hope this helps!
423 divided by 898 is 0.47104677...
Hope I could help! :)