Notăm:
m - vârsta mamei;
i - vârsta ioanei.
[tex]\it \left.\begin{aligned}\it m>i\ cu\ 24\Rightarrow m=i+24\\ \\ \it m>i\ de\ 3\ ori\ \Rightarrow\ m=3i\end{aligned}\right\}\ \Rightarrow\ 3i=i+24|_{-i}\Rightarrow 2i=24|_{:2}\Rightarrow i=12\ ani[/tex]
