2?7 + 3?7 = - 5?7
5?11 - 2?11 = - 3?11
8?3 - 10?3 = - -2?3
??5 + 2??5 = - 3??5
4³?5 - 6³?5 = - -2³?5
?7 + ?7 = - 2?7
?27 + ?3 = - 4?3
3?5 + ?20 = - 5?5
?25 - ?4 + ?16= - 7