The midpoint AB is M (-2,-4), If the coordinates of A are (-8,-5), what are the coordinates of B?

Question

find the missing midpoint

Answer 1

The midpoint M should have the average of the co-ordinates of A and B so if M=(-2,-4) and A= (-8,-5) and B= (x, y)

then -2 = (x+(-8))/2 and -4 = (y+(-5))/2

-4 = x-8 and -8 =y -5

so x= 4 and y = -3

Answer 2

2*(-2) - (-8) = -4 + 8 = 4

2*(-4) - (-5) = -8 + 5 = -3

Other endpoint = B = ( 4 , -3 ).

By the way, the problem says "find the missing midpoint", but they really meant find the missing endpoint.