1)-6,2-3,4; 2) -6\frac{3}{4} \cdot(-\frac{11}{45}); 3)-19,68: (-0,8); 4) 16,32: (-16).

1) $$ -6.2 - 3.4 = -9.6 $$

2) $$ -6\frac{3}{4} \cdot(-\frac{11}{45}) = -\frac{27}{4} \cdot(-\frac{11}{45}) = \frac{27 \cdot 11}{4 \cdot 45} = \frac{3 \cdot 11}{4 \cdot 5} = \frac{33}{20} = 1\frac{13}{20} = 1.65$$

3) $$ -19.68: (-0.8) = 19.68 : 0.8 = 196.8 : 8 = 24.6$$

4) $$ 16.32: (-16) = -1.02$$

Ответ: 1) -9.6; 2) 1.65; 3) 24.6; 4) -1.02