Question 163851
M (8,6) is the midpoint of RS. The coordinates of S are (9,7). What are the coordinates of R?

The midpoint formula is:

M = [(x1 + x2)/2, (y1 + y2)/2]

We are given the midpoint to be (8,6).

We are also given point S to be (9,7).

We set it up this way:

(8,6) = [(x + 9)/2, (y + 7)/2]

We now equate (x + 9)/2 to 8 and solve for x and then we equate (y + 7)/2 to 6 and solve for y.

(x + 9)/2 = 8

Multiply both sides by 2.

x + 9 = 8 (2)

x + 9 = 16

x = 16 - 9

x = 7

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We now do the same for y.

(y + 7)/2 = 6

y + 7 = 6 (2)

y + 7 = 12

y = 12 - 7

y = 5

The coordinates of point R are (7, 5)

Did you follow?