Have you got PhotoShop ? Or Paint Shop Pro, which is an oldie but I use it.
If so, you need to go to 'Image' and click 'negative' ... I know the slides you have are negatives anyway, but if you click it, they become positives ! Easy peasy !
Someone may be able to suggest a freebie programme that is similar for you to use.
How many are there ? You can send them to me, attached to email(s) and I'll 'flip' for you ! I'll PM you my email ...