(2+√3)(1-√3)
2-2√3+√3-3
-1-√3
1)3450*3=10350
2)10350+3450=13800
3)13800:20=690
Ответ: 690
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879-(458+х)=231
879-458-х=231
-х=231-879+458
-х=-190
х=190
ответ: х=190
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951-(х-354)=882
951-х+354=882
-х=882-951-354
-х=-423
х=423
Ответ: х=423
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549-(425-х)=488
549-425+х=488
х=488-549+425
х=364
Ответ: х=364