The mean of the answer is 20.5 because you add all of the number together and divide by 6 because there's 6 numbers. I'm sorry, but I don't know how to do the standard deviation... Hope this helped!
The solution of such a system is the ordered pair that is a solution to both equations. To solve a system of linear equations graphically we graph both equations in the same coordinate system. The solution to the system will be in the point where the two lines intersect.