Combine like terms to simplify: H + g + h + g - g

Can someone me out here and the tell me the greatest common factor

Find the greatest common factor of the followig monomials 46g^2h and 34g^6h^6

Arace is 10 kilometers long. markers will be placed at the beginning and end of the race course and at each 500 meter mark. how many markers are needed to mark the course for the race?