Răspuns :
a+b=7
a+c=8
a+b+c=12
7+c=12
c=12-7
c=5 mere are calin
8+b=12
b=12-8
b=4 mere are bogdan
a+5+4=12
a+9=12
a=12-9
a=3 mere are ana
a+c=8
a+b+c=12
7+c=12
c=12-7
c=5 mere are calin
8+b=12
b=12-8
b=4 mere are bogdan
a+5+4=12
a+9=12
a=12-9
a=3 mere are ana