a+b+c=523
b=2c
c=a+5
avem 3 relatii
inlocuim relatia 3 in relatia 2
b=2(a+5)
inlocuim relaria b=2(a+5) in prima relatie
a+2a+10+a+5=523
4a+15=523
4a=508
a=508/4 => a= 127
de aici inlocuiesti
a=127
b=2c
c=a+5
c=127+5=> c= 132
b=2c
b=2*132
b= 264
daca facem suma a+b+c=532
127+132+264=523
Q.E.T.D