Whenever a quadratic equation is in the form
(i.e. the leading terms is 1), you can solve it by looking for two numbers that give 
when summed and 
when multiplied.
So, in your case,
So, we're looking for two numbers 
such that:
you can clearly check that these numbers are 3 and 4.
So we have the points (-5,1) for A and (0,6) for D. By using y=mx+b we can determine that y=x+6 which also can be rewritten as -x+y=6.
2x-y=0 Y=x-1 2x-x-1=0 x-1=0
Answer: 6
That chart is confusing ash, but median just refers to the middle value. Just put them in order (4,4,6,9,12) and then find the middle. In this case it's easy as there are an odd number of values. But if you have another question where there are an odd number, for example (4,4,6,10,12,15) find the two middle numbers, 4 and 9, add them (6+10=16) and then divide by 2 to find the number in between those two. (16/2=8)
Hope this helps!
