Вычислить 8-4 5/7= 6 3/8 +2 7/8= 7 4/15 -3 11/15= Решить уравнение 6 7/9 - х= 4 2/9

Вычислим значения выражений:

1) 8 - 4 5/7 = 8 - 4 - 5/7 = 4 - 5/7 = 3 + 1 - 5/7 = 3 + 7/7 - 5/7 = 3 + (7 - 5)/7 = 3 + 2/7 = 3 2/7;

2) 6 3/8 + 2 7/8 = 6 + 2 + 3/8 + 7/8 = 8 + (3 + 7)/8 = 8 + 10/8 = 8 + 1 2/8 = 8 + 1 1/4 = 9 1/4;

3) 7 4/15 - 3 11/15 = 7 - 3 + 4/15 - 11/15 = 4 + 4/15 - 11/15 = 4 + (4 - 11)/15 = 4 - 7/15 = 3 + 1 - 7/15 = 3 + 15/15 - 7/15 = 3 + (15 - 7)/15 = 3 + 8/15 = 3 8/15;

Решим уравнение:

6 7/9 - х = 4 2/9;

6 7/9 - 4 2/9 = х;

х = 6 - 4 + 7/9 - 2/9;

х = 2 + (7 - 2)/9;

х = 2 + 5/9;

х = 2 5/9.

Ответ: х = 2 5/9.