Tata - t
Fiul - f
[tex] \left \{ {{t\ =\ \ \ 3f} \atop {t\ =f+28}} \right. \left \{ {{f+28=3f} \atop {t\ =f+28}} \right. \left \{ {{3f-f=28} \atop {t\ =f+28}} \right. \left \{ {{2f\\ =\\ \\ 28} \atop {t\ =f+28}} \right. \left \{ {{f\\ =\\ 14} \atop {t=f+28}} \right. \left \{ {{f=14} \atop {t=42}} \right. [/tex]
Raspuns: tata are 42 de ani, iar fiul are 14 ani.
