Ответ:

а) \[\frac49\cdot\frac{63}{64}\cdot\frac27=\frac18\]

б) \[\left(\frac12\right)^2\cdot\frac56\cdot\frac7{15}=\frac14\cdot\frac56\cdot\frac7{15}=\frac7{72}\]

в) \[\left(1-\frac13\right):\left(\frac13-\frac14\right)=\frac23:\frac1{12}=8\]

Ответ: а) \(\frac18\); б) \(\frac7{72}\); в) 8.