12 13/45 - ( у - 5 17/45 ) = 3 23/45
553/45 - ( у - 242/45 ) = 158/45
у - 242/45 = 553/45 - 158/45
у - 242/45 = 395/45
у = 395/45 + 242/45
у = 637/45 = 14 7/45
12 13/45 - ( 14 7/45 - 5 17/45 ) = 3 23/45
553/45 - ( 625/45 - 242/45 ) = 158/45
553/45 - 395/45 = 158/45
158/45 = 158/45