Help please :)

I trying to filter out content pages by multiple categories:

I have Umbraco.DropDownMultiple in frontend, using webAPI storing these values in List<string>

but how to filter out them regards what categories or multicategories selected, my code below:

List in the model: public List<string> Category { get; set; } 

 var pages = Services.ContentService.GetDescendants(3000); 

pgs = pages.Where(x => x.GetValue("mycat").ToString() == Category.FirstOrDefault()); - filtering just by first one. but how to filter using all Category list? Thank you