How many cases are required to test the tax system specification as described below, using a decision table which is not collapsed?
Tax system
A tax system needs to be updated due to new legislation. For a person with a salary of less than € 20.000 and who is married, the tax needs to be recalculated. If the person also has more than two and less than five children, an additional 10% reduction is applicable.

As a Test Analyst you are involved in the early stages of an acceptance test for a Product Data Management system.You are asked to write test designs and test cases based on use cases. An early version of the system is already available. It is expected that many things will change (including the user interface) during implementation of the new version.
The tests will be conducted by end-users with much domain knowledge who have also been involved in the project defining the user requirements (in the format of use cases) and reviewing other documentation.
What Is the BEST option regarding the level of detail and documentation required for test cases in the project?

Based on the classification tree shown below, using the pairwise testing technique how many test cases are required to test all pairs?