вычислите (5 3/4 - 4 8/9 ) 2 + 67 1/2 :2 1/7 ПРОШУ

2/7 + 3/8 = 16/56 + 21/56 = 37/56,

5/6 - 4/9 = 15/18 - 8/18 = 7/18,

3 1/8 + 2 5/6 = 3 3/24 + 2 20/24 = 5 23/24,

5 11/12 - 3 7/18 = 5 33/36 + 3 14/36 = 8 47/36 = 9 11/36

спасибо!