Решите уравнение( 4 целых 8 21+z)- 7 целых 13 21 одинаково

(4 8/21 + z) - 7 13/21 = 2 12/21;

4 8/21 + z = 2 12/21 + 7 13/21;

4 8/21 + z = 2 + 7 + 12/21 + 13/21;

4 8/21 + z = 9 + (12 + 13)/21;

4 8/21 + z = 9 + 25/21;

4 8/21 + z = 9 + 1 (25 - 1 * 21)/21;

4 8/21 + z = 9 + 1 (25 - 21)/21;

4 8/21 + z = 9 + 1 4/21;

4 8/21 + z = 9 + 1 + 4/21;

4 8/21 + z = 10 + 4/21;

4 8/21 + z = 10 4/21;

z = 10 4/21 - 4 8/21;

z = 10 - 4 + 4/21 - 8/21;

z = 6 + (4 - 8)/21;

z = 6 - 4/21;

z = 5 + 1 - 4/21;

z = 5 + 21/21 - 4/21;

z = 5 + (21 - 4)/21;

z = 5 + 17/21;

z = 5 17/21.

Ответ: z = 5 17/21.