Ответ:

  1. \[\left(\frac{3}{16}+1\frac15\right)\cdot\frac1{32}=\frac{79}{80}\cdot\frac1{32}=\frac{79}{2560}.\]
  2. \[\left(\frac78-2\frac3{20}\right)\cdot\frac1{48}=\left(\frac{35-88}{40}\right)\cdot\frac1{48}=-\frac{53}{1920}.\]
  3. \[\left(\frac1{28}+\frac1{35}\right):\frac1{91}=\frac{9}{140}\cdot91=\frac{819}{140}=\frac{117}{20}=5\frac{17}{20}.\]

Ответ: 1) \(\frac{79}{2560}\); 2) \(-\frac{53}{1920}\); 3) \(5\frac{17}{20}\).