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afla nr a ,dacă ab+ac=520 si b+c =52

Răspuns :

ab+ac=520
a(b+c)=520
dar stim ca 
b+c =52
a x 52 = 520
a=520:52
a=10
ab+ac=520 --> a x (b+c)=520 --> a x 52=520 --> a= 520:52 --> a= 10