Ответ:

  1. \(6.45 \cdot 17 - (171 - 37.08) : 31 = 109.65 - 133.92 : 31 = 109.65 - 4.32 = 105.33\)

  2. \(8.64 : \frac{4}{5} + 2\frac{3}{20} = 8.64 \cdot \frac{5}{4} + 2.15 = 10.8 + 2.15 = 12.95\)

  3. \((3.275 + 1.725) \cdot (9.16 - 5.74) = 5 \cdot 3.42 = 17.1\)

  4. \((5 \cdot 1.284 - 5.7) \cdot 4.25 = (6.42 - 5.7) \cdot 4.25 = 0.72 \cdot 4.25 = 3.06\)

Ответ: а) 105,33; б) 12,95; в) 17,1; г) 3,06.