The avenues in a particular city run north to south and are numbered consecutively with 1st Avenue at the western border of the city . The streets in the city run east to west and are numbered consecutively with 1st Street at the southern border of the city . For a festival, the city in not allowing cars to park in a rectangular region bordered by 6th Avenue to the west , 10th Avenue to the east, 11the street to the south , and 13th Street to the north . If x is the Avenue number and y is the street number, which of the following systems describes the region in which cars are not allowed to park ?