Răspuns :

Dianageorgiana794id

Răspuns:

a+b+c=7

a) 2a+2b+2c =2(a+b+c)=2·7=14

b) a•13+b•13+c•13+21 =13(a+b+c)+21=13·7+21=91+21=112

c)400-(5a+5b+5c)​=400-5(a+b+c)=400-5·7=400-35=365

Nicutheodoraid

Explicație pas cu pas:

a) 2a +2b + 2c=

=2×(a+b+c)

=2×7

=14

b) a×13+b×13+c×13+21=

=13×(a+b+c)+21

=13×7+21=91+21

=112

c) 400-(5a+5b+5c)=

=400-5(a+b+c)

=400-5×7

=400-35

=365

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