(6 11/12-2y)-5 1/24=7/8
(6 11/12 - 2у) - 5 1/24 = 7/8 6 11/12 - 2у = 7/8 + 5 1/24 6 11/12 - 2у = 21/24 + 5 1/24 6 11/12 - 2у = 5 22/24 = 5 11/12 (дробь 22/24 сократили на 2) 2у = 6 11/12 - 5 11/12 2у = 1 у = 1/2