(-6,7)+(-2,8) = (-6-2, 7+8) = (-8, 15)
(2,73):(-2,1) = (2/-2, 73/1) = (-1, 73)
(-4 2/7) - (-1 5/14) - (-1 5/14) = (-4 2/7) + (1 5/14) + (1 5/14) = -4 + 2 + 1 + 1 + 5/14 + 5/14 = 0 + 7/14 + 5/14 = 0 + 12/14 = 0 + 6/7 = 6/7
(-6,7)+(-2,8) = (-6-2, 7+8) = (-8, 15)
(2,73):(-2,1) = (2/-2, 73/1) = (-1, 73)
(-4 2/7) - (-1 5/14) - (-1 5/14) = (-4 2/7) + (1 5/14) + (1 5/14) = -4 + 2 + 1 + 1 + 5/14 + 5/14 = 0 + 7/14 + 5/14 = 0 + 12/14 = 0 + 6/7 = 6/7