How the heck do I figure out this problem?

I might be stupid, but can somebody help walk me through the steps to reach the solution to this problem?





1. What is the average (arithmetic mean) of 7n+1 and n-7?





(A) 4n-3


(B) 4n+3


(C) 4n+4


(D) 8n-6


(E) 8n+8








Thanks! =)How the heck do I figure out this problem?
Well, to take the average of a set of numbers, you add all of the numbers in the set, and divide by the total number of numbers in the set. You have a set of two: (7n+1) and (n-7).


So, plugging into the formula to calculate the average, you would get:


((7n+1)+(n-7))/2


You can simplify the numerator by distributing the addition sign and combining like terms.


(7n+1+n-7)/2


(8n-6)/2


Now, you can factor a two out of the numerator, since it's a common factor in both terms..


2(4n-3)/2


And the 2 in the numerator and the denominator cancel out, leaving you with


4n-3How the heck do I figure out this problem?
avg can be found using this formula = sum of numbers/ no of numbers





steps


1) (7n+1 + n-7)/ 2 ' / ' means divide


2) 7n+n + 1-7/2


3) 8n + (-6)/2


4) 8n-6/2


5) 8n/2 - 6/2


6) 4n-3





so your answer is (A)