[tex]\left\{\begin{matrix}
3p + 4c = 36.50 \: | \times ( - 2)\\
6p + 7c = 67.25\end{matrix}\right.[/tex]
[tex]\left\{\begin{matrix}
- 6p - 8c = - 73\\
6p + 7c = 67.25\end{matrix}\right.[/tex]
[tex] - 6p + 6p - 8c + 7c = - 73 + 67.25[/tex]
[tex] - c = - 5.75 \: | \times ( - 1)[/tex]
[tex]c = 5.75 \: lei[/tex]
[tex]3p + 4c = 36.50[/tex]
[tex]3p + 4 \times 5.75 = 36.50[/tex]
[tex]3p + 23 = 36.50[/tex]
[tex]3p = 36.50 - 23[/tex]
[tex]3p = 13.5[/tex]
[tex]p = 13.5 \div 3[/tex]
[tex]p = 4.5 \: lei[/tex]