Ответ:
1)41 9/21+x=45 11/21
870/21 + x = 956/21
290/7 + x = 956/21
x = 956/21 - 290/7
x = 86/21
2) (9 21/63-x)-3 15/63=2 11/63
(588/63 - x) - 204/63 = 137/63
(28/3 - x) - 204/63 = 137/63
128/21 - x = 137/63 - 128/21
-x = 137/63 - 128/21
-x = - 247/63
x = 243/63