Ответ:

  1. \(236+189+308=733\).
  2. \((200-30)\cdot5=850\); \(50\cdot4+90\cdot3=470\); \(27:(9\cdot3)=1\); \(300+90:3=330\); \(70\cdot3+80:10=218\); \(68:2:2=17\).