Need mid point?

Question

Find the midpoint of (5,7) and (-3,9)

Answer 1

[(x1+x2)/2, (y1+y2)/2]
(1,8)

Answer 2

Do it the hard way:
y= mx + b is the equation of a straight line
y(x=5) = m(5) + b = 7
y(x=-3) = m(-3) + b = 9, then subtract the second from the first
8m = -2, and m = -1/4
Take the first and put in m
y(x=5) = (-1/4)(5) + b = 7
b = 7 + 5/4 = 28/4 + 5/4 = 33/4

then the straight line is y = -x/4 + 33/4 = (33-x)/4
Mid point is when x is between -3 and 5, which is +1; now plug into your straight line formula to get the corresponding y:

y(x=1) = (33-1)/4 = (32)/4 = 8

You could do this by inspection, but here is the long way