3 Simple Queries SQL Student Question, Query Errors in Microsoft Access
the first is simple access  has no !=
SELECT TripName AS Ausdr1
FROM Trip
WHERE ([State])&lt;&gt;'NH';

the form of the secnd is wrong and you should start to use proper JOINs a comma for tables means always a cROSS JoiN, which can be useful, but nit in this case
also strings must always be in quotes
SELECT TripName , MaxGrpSize 
FROM Trip, TripGuides
WHERE ((([Type])='Hiking') AND (([GuideNum])='BR01'));

the last  us simple bith tables have the column ´CustomerNum´, so you have to tell access which one you wantg, but i guess it is a joining column.
SELECT DISTINCT  LastName, FirstName, [Customer].CustomerNum, ReservationID
FROM Customer, Reservation
WHERE TripDate = '2018-12';

what i mean by proper joining:
SELECT DISTINCT  LastName, FirstName, c.CustomerNum, ReservationID
FROM Customer C INNER JOIN Reservation r ON c.CustomerNum = r.CustomerNum
WHERE TripDate = '2018-12';

I don#t know ou complete tables , so i am only guessing