PLEASE HELP FAST 20 POINTS! Housing prices are often reported using a median. Why is median used in this case? Would arithmetic mean or mode reasonable for comparing housing prices?

Step-by-step explanation:

The red line in the graph above measures the median home price, and this is often a better "average" for us to be used with home prices and home values. Unfortunately, it is not as easy to calculate and it does not work well with tiny data sets, so we often only see it used with very large data sets (like whole Cities, States, etc.) produced by the large real estate aggregators. Additionally, not many real estate agents know how to generate them for neighborhoods or zip codes (but we can at the Tallahassee Real Estate Blog :)).

point a is the center of the circle that passes through points e, f, and g and the center of the circle that passes through points x, y, and z.

check above link.

graphically?   well, you graph them both, the solutions is where they both intersect each other, since there are two solutions, meaning they will meet twice, or namely the linear will run into the quadratic curve twice, and where they meet, those x,y coordinates are the solutions to the system.