Since, D is the mid point of BC. So, coordinate of BC are (2x2+x3,2y2+y3)
Given, G(7,5) is the centroid of ΔABC ∴7=32+x2+x3
and 5=33+y2+y3 ⇒x2+x3=21−2
and y2+y3=15−3 ⇒x2+x3=19
and y2+y3=12 ⇒2x2+x3=219
and 2y2+y3=6 ∴ Coordinate of D are (219,6)