[tex] \begin{cases} - 4x + 2y = 1 | \times ( - 5) \\ - 11x + 5y = 2.5 | \times 2 \end{cases}[/tex]
[tex]\begin{cases}20x - 10y = - 5 \\ - 22x + 10y = 5 \end{cases}[/tex]
[tex]20x + ( - 22x) = - 5 + 5 \\ - 2x = 0 | \div ( - 2) \\ x = 0[/tex]
[tex]20 \times 0 - 10y = - 5 \\ 0 - 10y = - 5 \\ - 10y = - 5 | \div ( - 10) \\ y = \frac{5}{10} \\ y = 0.5[/tex]
[tex]\begin{cases} x = 0 \\ y = 0.5\end{cases}[/tex]
