Development tools can be viewed in menu-File-Options.
In Development Tools-Insert-Form Control-Insert Checkbox into B6 Cell,
Right-click the check box to format the control, and set the cell link of the check box to B6, that is, it is true when the check box is selected and false when it is not selected. Set these check boxes repeatedly.
Enter the formula for J2:
= = Sum (-(B6:B25))
Press SHIFT+CTRL+ enter.
Do it.