Identify the corresponding lengths on the original figure and the image (or two figures).
Use the scale factor formula: scale factor = (image length) / (original length).
If the enlargement is from original to image, the scale factor is positive.
If the figure is a reduction, the scale factor will be less than 1.
If the figure is an enlargement, the scale factor will be greater than 1.
If using areas: scale factor for area = (image area) / (original area) and take the square root for length scale factor.
If using volumes: scale factor for volume = (image volume) / (original volume) and take the cube root for length scale factor.
If two scale factors are given between consecutive steps, multiply them to get the overall scale factor.