Пошаговое объяснение:
1) 15/20 - 11/36 = 3/4 - 11/36 = 27/36 - 11/36 = 16/36 = 4/9
2) 6/11 * 4/9 = 2/11 * 4/3 = 8/33
3) 8/33 * 21/29 = 8/11 * 7/29 = 56/319
4) 6. 6/7 : 16/21 = 48/7 * 21/16 = 3/1 * 3/1 = 9/1 = 9
5) 56/319 + 9 = 9. 56/319
