Răspuns :
le aduni si da 2a +2b+2c=1200 totul impartim la 2
a+b+c=600
inlocuim
300+c=600
c=300
b+300=500
b=200
a+200=300
a=100
a+b+c=600
inlocuim
300+c=600
c=300
b+300=500
b=200
a+200=300
a=100
2A+2B+2C=1200
1200:2=600
A+B+C=600
300+c=600
c=300
b+300=500
b=200
a+200=300
a=100
1200:2=600
A+B+C=600
300+c=600
c=300
b+300=500
b=200
a+200=300
a=100