What is the mathematical relationship between the scale factor for lengths and the scale factor for areas

The ratio of the area of one figure to the area of another, similar figure is equal to the square of the scale factor between the two figures. The ratio of the volume of one figure to the volume of another, similar figure is equal to the cube of the scale factor between the two figures.

if you are saying purchasing 3 social media ads and one newspaper ad counts as one purchase then there are:

6 purchases

if you are asking how many of each then:

18 social media ads

6 newspaper ads

could you provide figure.