Linq question

i have this

var projectsList = BL<IProjectSupervisorBl>.GenericBL.GetProjectsIdsByCoreUserId(UserLogged.Id).ToList();

and i have a var dataTasks with the projectId ammong other properties

i nedd to extract fom data

var filteredData where project id in projectList

How could i do this...

this is my first days in linq