a fost răspuns

a+b+c=57
2a+b+2c=73
calculati : (a+c) x (5a+2b+5c)

Răspuns :

2(a+c)+b=73
2(57-b)+b=73
114-b=73
b=41
a+c=57-41=16
(a+c)x[5(a+c)+2b]=16x(5x16+82)=178

Buniask
a+b+c=57
a+a+b+c+c=76, 57+a+c=73, a+c=16
(a+c)x(5a+2b+5c) = 
=(a+c)x(2a+2b+2c+3a+3b)=
=(a+c)x[2(a+b+c)+3(a+c)]
=16 x (2x57+3x16)=
=16 x (114+48)=
=16 x 162
=2592

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