Ответ:

  1. \(207 \cdot 3 - 704 : 8 = 621 - 88 = 533\).
  2. \(684 : 9 + (506 - 102 \cdot 3) = 76 + (506 - 306) = 76 + 200 = 276\).
  3. \(736 \cdot 4 + (607 - 428 : 4) = 2944 + (607 - 107) = 2944 + 500 = 3444\).

Ответ: 533; 276; 3444.