calculation of negative hours in excel

some people take too many hollidays so I want to recalculate yhere hours nad need in excel the possibillity to calculateABCD 1TimeRecalcRecalc in numbers206:5506:55                   6,92 3-12:50-12:50#WAARDE! 4-12:5012:50                 12,83 507:0007:00                   7,00 606:4007:00                   7,00 707:0007:00                   7,00 806:5506:55                   6,92 907:0007:00                   7,00 1007:0007:00                   7,00 1107:1607:16                   7,27 12-12:50#NAAM?#NAAM? 13-12:50ONWAAR                        -   1407:0007:00                   7,00 1507:0007:00                   7,00         In C12 I used =ALS(LINKS(I5)=-";(SUBSTITUEREN(I5;"-";""));I5) In C2 I used =IF(LEFT(AB12;1)="-";-(--MID(AC12;2;10));AC12)
who can help