Answer:
QD = 13
Explanation:
According to the Centroid theorem of a triangle, the Centroid is ⅔ of the distance from every vertex angle to the midpoint of the side opposite to each of them.
By this we can deduce that:
QD = ⅔(QD + DK)
Substitute
QD = ⅔(QD + 6.5)
Multiply both sides by 3
3*QD = 2(QD + 6.5)
3QD = 2QD + 13
Subtract both sides by 2QD
3QD - 2QD = 13
QD = 13