a+b = 300 ,
b+c= 500,
a +c=400
se aduna toate
2a+2b+2c=300+400+500
2(a+b+c)=1200
a+b+c= 600 si
a+b = 300
⇒ 300 + c = 600
c= 600 - 300 = 300
c= 300
a +c=400⇒a=400-c=400-300 =100
a=100
a+b=300
100 + b = 300 ⇒b = 300 -100 = 200
⇒b=200
deci a=100, b=200 si c=300
