List all the sales people in the Northwest US.
Northwest is name of SalesTerritory; US is the CountryRegionCode;
SELECT T2.BusinessEntityID FROM SalesTerritory AS T1 INNER JOIN SalesPerson AS T2 ON T1.TerritoryID = T2.TerritoryID WHERE T1.Name = 'Northwest' AND T1.CountryRegionCode = 'US'