Сделайте деяние: 1) 12/17-3/17; 2)3/7+2/7; 3) 3 1/5+5 2/5; 4) 9

Чтоб выполнить деяния будем отымать или добавлять в числителе, а знаменатель не меняется:

1) 12/17 - 3/17 = (12 - 3)/17 = 9/17;

2) 3/7 + 2/7 = (3 + 2)/7 = 5/7;

3) 3 1/5 + 5 2/5 = 3 + 5 + 1/5 + 2/5 = 8 + (1 + 2)/5 = 8 + 3/5 = 8 3/5;

4) 9 1/4 + 3/4 = 9 + 1/4 + 3/4 = 9 + (1 + 3)/4 = 9 + 4/4 = 9 + 1 = 10;

5) 8 3/7 - 4 = 8 - 4 + 3/7 = 4 + 3/7 = 4 3/7;

6) 6 11/27 - 5/27 = 6 + 11/27 - 5/27 = 6 + (11 - 5)/27 = 6 + 6/27 = 6 + (2 * 3)/(3 * 9) = 6 2/9;

7) 1 - 2/5 = 5/5 - 2/5 = 3/5;

8) 10 4/21 - (4 10/21 + 3 19/21) = 1 17/21.

1. 4 10/21 + 3 19/21 = 7 + (10 + 19)/21 = 7 + 29/21 = 7 + 1 8/21 = 8 8/21.

2. 10 4/21 - 8 8/21 = 2 + (4 - 8)/21 = 2 - 4/21 = 1 + 21/21 - 4/21 = 1 17/21.