In the $xy$-plane, the point ($6,3$) is the midpoint of the line segment with endpoints ($x,5$) an ($9,y$). What is the value of $x+y$ ?

Question

kainui · Answer

It might help to draw a picture. I'll give an example of a similar problem, let's think of just one axis. If I give you the number 7 and I say it's the mid point of 3 and another number, what's the other number? Well it should be the same difference away. So 7-3=4 is the difference, but it's on the other side of 7, so 7+4=11 is the other point. Sure enough, 7 is right between 3 and 11.

theraggedydoctor · Answer

Oh okay.. Thank you.

kainui · Answer

tell me your answer and reasoning and I can check it for you =)