On a coordinate system, the segment joining the points (3,8) and (9,16) has the same midpoint as the line segment joining the points (8,11) and (x,13). What is the value of x?
I think x=3
Mid-point of (3,8) and (9,16)
=((3+9)/2, (8+16)/2)
=(6,12)
Mid-point of (8,11) and (x,13)
=((8+x)/2, (11+13)/2)
=((8+x)/2, 12)
To have the same mid-point, the x- and y-coordinates of the mid points must match.
so
(8+x)/2 = 6
Solve for x.