Answer:
14
Step-by-step explanation:
To get the mean, you have to add all the numbers together, and then divide them by how many numbers there are. Here, i'll show you.
There are 6 numbers, including  , which we need to find out.
, which we need to find out. 
The Equation:  
- We can simplify this equation into,  
To find  , we can do the inverse, and multiply
, we can do the inverse, and multiply  by
 by  .
.
(The 6 on the left side of the equation is then cancelled out)
For this final equation to be true,  would have to equal
 would have to equal  .
.
<em>Hope the rest of your math goes well :)</em>