For the dilation, do, k = (10, 0) → (5, 0), the scale factor is equal to

The dilation factor is computed by dividing the length of the side of the second figure by the length of the side of the first figure. From the given coordinates of the point, we can say that the distance is divided by 2. Thus, the answer in the dilation factor is 1/2 or 1:2. 

place the card on a flat dry surface