Răspuns :
a+b=30
a+c=40
b+c=50
2a+2b+2c=30+40+50
2(a+b+c)=120
a+b+c=120÷2=60
a+b=30=>c=30
a+c=40=>b=20
b+c=50=>a=10
a+c=40
b+c=50
2a+2b+2c=30+40+50
2(a+b+c)=120
a+b+c=120÷2=60
a+b=30=>c=30
a+c=40=>b=20
b+c=50=>a=10