Harsh and Manisha collect sea shells.Harsh began a holiday with 172 sea shells and Manisha began with 20 shells.Each day...

Harsh and Manisha collect sea shells.Harsh began a holiday with 172 sea shells and Manisha began with 20 shells.Each day of the holiday Harsh found 39 shells and Manisha found 77 shells on the beach,by the end of the holidays they had the same number of sea shells in total.How long was the holidays