Enter your equations one by one in CAS, pressing Enter to start a new row for each of your equations.
Select each of the rows with an equation in them by clicking the boxes with a row number. You’ll know that the row is selected when the box with the row number has turned purple. To select more than one box at a time, hold down the Shift key, click the box of the first equation and then click the box with the row number of the last equation.
If you get as the output, the system of equations has no solution. If GeoGebra returns one of the variables as a function , then the system of equations has infinitely many solutions.