Ответ:
а) \(\frac49\cdot\left(-\frac38\right)=-\frac{12}{72}=-\frac16\).
б) \(\frac56-\frac49\cdot\frac{15}{21}=\frac56-\frac49\cdot\frac57=\frac56-\frac{20}{63}=\frac{105-40}{126}=\frac{65}{126}\).
Ответ: а) \(-\frac16\); б) \(\frac{65}{126}\).
а) \(\frac49\cdot\left(-\frac38\right)=-\frac{12}{72}=-\frac16\).
б) \(\frac56-\frac49\cdot\frac{15}{21}=\frac56-\frac49\cdot\frac57=\frac56-\frac{20}{63}=\frac{105-40}{126}=\frac{65}{126}\).
Ответ: а) \(-\frac16\); б) \(\frac{65}{126}\).