Răspuns :
c-f=12-2=10
c=10+f
c+f=56
10+f+f=56
10+2f=56
2f=56-10
2f=46
f=46:2
f=23
c=23+10
c=33 ani
unde c - crina
f - frate
c=10+f
c+f=56
10+f+f=56
10+2f=56
2f=56-10
2f=46
f=46:2
f=23
c=23+10
c=33 ani
unde c - crina
f - frate
c-f=12-2=10
c+f=56
c=f+10
f+10+f=56
2f+10=56
2f=56-10
2f=46
f=46:2
f=23
c=23+10
c=33