X + y - 5
При x = -10, y = -5:
x + y - 5 = -10 - 5 - 5 = -20
При x = -1 11/21, y = -2 5/14:
x + y - 5 = -1 11/21 - 2 5/14 - 5 = -32/21 - 33/14 - 5 = -64/42 - 99/42 - 210/42 = -373/42 = -8 37/42
При x = -4,5; y = -3,5:
x + y - 5 = -4,5 - 3,5 - 5 = -8 - 5 = -13