Решите в)2 1/7а+3 9/14а=11 1/7 -1 1/21-2 3/14

2 1/7а+3 9/14а=11 1/7 -1 1/21-2 3/14

1) 2 1/7 = 15/7
    3 9/14 =51/14
   11 1/7 = 78/7
    1 1/21 = 22/21
    2 3/14 = 31/14

2) Приводим к общему знаменателю:
    30/14 a+51/14 a = 81/14 a.
    468/42 - 44/42 - 93/42 = 331/42.

3) 81/ 14 a = 331/42
a = 331*14/42*81 = 331/243.