Ответ:

  1. \(3.4\cdot6.2=21.08\), \(8.4:0.4=21\).
    \(285.7+21.08-21=285.78\).
  2. \(35.83+2.71=38.54\), \(38.54\cdot2.5=96.35\).
    \(100.35-96.35=4\).

Ответ: 285,78; 4.