In order to dilate the given points, multiply each coordinate of each point by the scale factor.
In this case you have the scale factor k = 1/2, then, you have:
D(8,6) => D'(8*1/2 , 6*1/2) = D'(4 , 3)
I(2,-8) => I'(2*1/2 , -8*1/2) = I'(1 , -4)
G(-2,10) => G'(-2*1/2 , 10*1/2) = G'(-1 , 5)
Then, the dilated triangle is:
