You can use Spreadsheet in GeoGebra  to calculate your net income. In Item 2 below, there’s a template you can follow. At the end of the entry, there’s an example so you can see how you can use the template in practice. 
     That said, it’s often better to use Excel , since it has more built-in tools like charts and formatting options than there are in GeoGebra. 
     GeoGebra Instruction 1
Spreadsheet Spreadsheet     under         View     in         Menu.         GeoGebra     doesn’t         display         the         equal         sign         before         each         formula,         nor         the         multiplication         symbol         (*)         between         the         cell         names,         but         you         must         type         them         nonetheless.         
      
Example 1
You have a fixed salary of $ per month. Your normal workweek is 40 hours, and you receive an additional to your hourly rate when working overtime during weekdays, and when working overtime on Sundays. One month, you work 15 hours’ overtime during the week and 6 hours’ overtime on Sundays. of your salary goes to taxes. What is your net income?
Follow Item 2 and insert the numbers from the exercise. Your spreadsheet should look like the one in the image below.