а) \[ \frac{3}{5} : (-\frac{11}{15}) = \frac{3}{5} \cdot (-\frac{15}{11}) = -\frac{3 \cdot 15}{5 \cdot 11} = -\frac{45}{55} = -\frac{9}{11} \]
б) \[ 0,56 : 0,8 = \frac{56}{100} : \frac{8}{10} = \frac{56}{100} \cdot \frac{10}{8} = \frac{56 \cdot 10}{100 \cdot 8} = \frac{560}{800} = \frac{7}{10} = 0,7 \]
в) \[ -0,45 : (-0,15) = -\frac{45}{100} : (-\frac{15}{100}) = \frac{45}{100} \cdot \frac{100}{15} = \frac{45 \cdot 100}{100 \cdot 15} = \frac{45}{15} = 3 \]
г) \[ -\frac{1}{7} : 0,7 = -\frac{1}{7} : \frac{7}{10} = -\frac{1}{7} \cdot \frac{10}{7} = -\frac{1 \cdot 10}{7 \cdot 7} = -\frac{10}{49} \]
Ответ: а) -9/11; б) 0,7; в) 3; г) -10/49