Question

Aflati trei numere naturale a,b,C care verifica simultan egalitatile:
a+b=28; b+c=16;c+a=20.

Answer 1

2(a+b+c)=28+16+20=
a+b+c=64:2=32
a+b=28
c=32-28=4
b+c=16
b=16-4=12
a=28-12=16

Answer 2

a+b     = 28

    b+c = 16 si

a    +c = 20      adunam termen cu termen ...

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2(a+b+c) = 64

   a+b+c = 32   =>  28+c = 32 => c =   4 ;

                               a+16= 32 => a = 16 ;

                               b+20= 32 => b = 12