c-caiete studențeşti
b-blocuri de desen
[tex]\left\{\begin{matrix}
4c + 3b = 69 \: | \times 2 \\
5c + 2b = 67 \: | \times ( - 3) \end{matrix}\right.[/tex]
[tex]\left\{\begin{matrix}
8c + 6b = 138\\
- 15c - 6b = - 201\end{matrix}\right.[/tex]
[tex]8c - 15c + 6b - b = 138 - 201[/tex]
[tex] - 7c = - 63 \: | \div ( - 7)[/tex]
[tex]c = 9 \: lei[/tex]
[tex]4c + 3b = 69[/tex]
[tex]4 \times 9 + 3b = 69[/tex]
[tex]36 + 3b = 69[/tex]
[tex]3b = 69 - 36[/tex]
[tex]3b = 33 \: | \div 3[/tex]
[tex]b = 11 \: lei[/tex]