assuming M is midpoint of RS
the midpoint formula is
x term of the midpoint is average of the x value of the 2 points
y term of the midpoint is average of the y value of the 2 points
if R is (x,y)
S is (6,1)
x value of midpoint is 4
x value of S is 6
x value os R is x
so
average of x and 6 is 4,
(x+6)/2=4,
x+6=8,
x=2
y value of midoint is 2
y value of S is 1
y value of R is y
average of 1 and y is 2
(y+1)/2=2
y+1=4
y=3
the midpoint is (2,3)
