1) 2.8•(-3,9)-76,15: 15,23;
2) 34,68: (7,11+1,56)+46: (2,45-1,65);
3)(0,62+0,56-2,29) • (8,44-5,34);
4)62,93+(12,5-7,6+3,21): 0,1.

1) 2,8×(-3,9)-76,15÷15,23=-10,92-5=-15,92;

2) 34,68÷(7,11+1,56)+46÷(2,45-1,65)=61,5;

1. 7,11+1,56=8,67
2. 2,45-1,65=0,8
3. 34,68÷8,67=4
4. 46÷0,8=57,5
5. 4+57,5=61,5.

3) (0,62+0,56-2,29)×(8,44-5,34)=-3,441;

1. 0,62+0,56-2,29=1,18-2,29=-1,11
2. 8,44-5,34=3,1
3. (-1,11)×3,1=3,441.

4) 62,93+(12,5-7,6+3,21)÷0,1=144,03.

1. 12,5-7,6+3,21=4,9+3,21=8,11
2. 8,11÷0,1=81,1
3. 62,93+81,1=144,03.