Решить по действиям: 1 5/12 * (12/17 + 2 14/51) - 1 7/9= 2.1 7-16 + 1,05 - 3 7/12 + 6 4/15

1. 

5/12 * (12/17 + 2 14/51) - 1 7/9 = -82/153. 

1). 12/17 + 2 14/51 = 12/17 + 116/51 = (12 * 3)/(17 * 3) + 116/51 = 36/51 + 116/51 = 152/51; 

2). 5/12 * 152/51 = (5 * 152)/(12 * 51) = 760/612 = 190/153; 

3). 190/153 - 1 7/9 = 190/153 - 16/9 = 190/153 - (16 * 17)/(9 * 17) = 190/153 - 272/153 = -82/153. 

2.

17-16 + 1,05 - 3 7/12 + 6 4/15 = 4 11/15. 

1). 17 - 16 = 1; 

2). 1 + 1,05 = 2,05; 

3). 2,05 - 3 7/12 = 2 5/100 - 3 7/12 = 205/100 - 43/12 = (205 * 3)/(100 * 3) - (43 * 25)/(12 * 25) = 615/300 - 1075/300 = -460/300 = -92/60 = -1 32/60 = -1 8/15; 

4). -1 8/15 + 6 4/15 = -23/15 + 94/15 = 71/15 = 4 11/15.