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se stie ca a+b+c=7
calculati. 2a+2b+2c
10a+10b+10c
a×13+b×13+c×13+21


Răspuns :

2a+2b+2c=2(a+b+c)=2*7=14;
10a+10b+10c=10(a+b+c)=70;
13a+13b+13c+21=13(a+b+c)+21=91+21=112