Since y = 9 is a horizontal line, the parallel line must also be horizontal. All horizontal lines can be written as y = (a number). That number can be found as the y-coordinate in the ordered pair, which is -8.
16 red cars and 12 black cars. He put half of each colour in each box. Therefore he would put 8 red and 6 black in each box. 8 red + 6 black is 14. Therefore he would have 14 cars in each box.