A + I + Ir = 27 ani
A = Ir - 4 => Ir = A+4
I = Ir - 2 => Ir = I+2
A+4 = I+2
I = A +4-2
I = A + 2
A |___|
I |___|+2
Ir |___|+4
avem 3 segmente egale +2+4 = 27
27 - (2+4) = 27 - 6 = 21
21 : 3 = 7 (un segment egal)
A = 7
I = 7 + 2 = 9
Ir = 7 + 4 = 11
Verificare:
7 + 9 + 11 = 27
7 ani are Ana
9 ani are Ioana
11 ani are Irina