[tex]x\rightarrow\text{obecny wiek Zosi}\\y\rightarrow\text{obecny wiek Adama}\\\\\begin{cases}x-3=4(y-3)\\[2pt]x+1=2(y+1)\end{cases}\\\\\begin{cases}x-3=4y-12\\[2pt]x+1=2y+2\end{cases}\\\\\begin{cases}x-4y=-9\\[2pt]x-2y=1\end{cases}\\\\\text{*odejmuje drugie r\'ownanie od pierwszego*}\\\\x-4y-(x-2y)=-9-1\\x-4y-x+2y=-10\\-2y=-10\\y=5\\\\x-2\cdot5=1\\x-10=1\\x=11[/tex]
Odp. Adam ma 5 lat, a Zosia ma 11 lat.
