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 is not allowing cars to park in a rectangular region bordered by 6th avenue to the west, 10th avenue to the east, 11th 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?