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determinati a, b,c,d stiind ca abcd barat = abc barat +2009

Răspuns :

1000a+100b+10c+d=100a+10b+c+2000+9
1000a=2000,   a=2
100b=100a,     b=a=2
10c+d=10b+c+9,    
10c+d=20+c+9,  c=3, d=2

223+2009=2232