1. а) 3 5/8 + 1 2/3 = 29/8 + 5/3 = 87/24 + 40/24 = 127/24;
б) 4 4/9 - 2 5/6 = 40/9 - 17/6 = 80/18 - 51/18 = 29/18;
в) 6 7/12 + (5 3/40 - 4 8/15) = 79/12 + (203/40 - 68/15) = 79/12 + 203/40 - 68/15 = 790/120 + 609/120 - 544/120 = 855/120 = 171/24 = 57/8
4. 5 5/33 + у = 8 3/44
у = 355/44 - 170/33
у = 1065/132 - 680/132
у= 385/132 = 35/12
Ответ: у=35/12