If the midpoint between (18, y) and (20, -15) is (19, -5), find the value of y.

Question

anonymous · Answer

thanks so much

anonymous · Answer

@junyang96 can you help me with this?

anonymous · Answer

If we draw our points like this:
|dw:1424890286328:dw|
We can tell that since (19, -5) is the midpoint it means that the y-difference between (18, y) and (19,-5) is the same as the y-difference between (19,-5) and (20, -15) which is:
$$ -5 - (-15) = -5 + 15 = 10
$$What that means is that the y of (19, -5) is bigger than the y of (20, -15) by 10.
So that means that the y of (18, y) is bigger than the y of (19, -5) also by 10:
$$
y = -5 + 10 = 5
$$

anonymous · Answer

My (amazing) drawing was deleted for some reason
|dw:1424890853857:dw|
$ \Huge ☺ $

anonymous · Answer

the answer i came to was that y=5, is that correct?
@pitamar

anonymous · Answer

Ye, that's what I got up here too =)

anonymous · Answer

Ill tell yo if its correct when the work is graded

anonymous · Answer

Ok =)