The solution to this equation is x=4.6 because 19.32/4.2=4.6
Here is a model I have made (I'm not a great artist). There are 42 circles in total, placed in 7 columns. Each column has 6 circles. This model represents 42/7 by splitting 42 into 7 parts, which are the columns, and showing that each column has 6 circles, which is the answer to 42/7.
A year has 12 months so 1 month = 1/12 year. t = 3 months = 3/12 year = 1/4 year