Here, △ABC is equilateral.
(x1−4)2+(y1−5)2=(x2−4)2+(y2−5)2=(x3−4)2+(y3−5)2
⇒A,B,C are equidistant from the point (4,5)
∴(4,5) is the circumcentre.
As it is an equilateral triangle, so the centroid coincides with circumcentre.
(x1+x2+x33,y1+y2+y33)=(4,5)⇒x1+x2+x3=12, y1+y2+y3=15∴(y1+y2+y3)−(x1+x2+x3)=3