(0,0) is the origin of a graph, so both W and W' remain at the origin.
The other 3 vertices double in size:
If you multiply all the numbers in X, Y and Z by 2, they become the numbers in X', Y' and Z'.
X(1,2) x 2 = (1*2,2*2) = X'(2,4)
Y(4,2) x 2 = (4*2, 2*2) = Y'(8,4)
Z(3,0) x 2 = (3*2, 0*2) = Z'(6,0)
That means the scale factor is 2
