(5 8/15-4 7/10)•2 2/3-5/9 решить пример

(5 8/15 - 4 7/10) * 2 2/3 - 5/9 = 1 2/3

1) 5 8/15 - 4 7/10 = 5 16/30 - 4 21/30 = 4 46/30 - 4 21/30 = 25/30 = 5/6
2) 5/6 * 2 2/3 = 5/6 * 8/3 = 20/9 
3) 20/9 - 5/9 = 15/9 = 5/3 = 1 целая 2/3

Пояснения:
8/15 = 16/30 - доп.множ. 2
7/10 = 21/30 - доп.множ.3
2 целых 2/3 = (2*3+2)/3 = 8/3
15/9 = 5/3 - сократили на 3