1) \( 3 r-4 s+2 t = -22 \quad |·2 \)
2) \( 5 r+4 t = -6 \)
3) \( -2 r+5s = 21 \)
\( \begin{array}{l}{\text { 1) } 6 r-8 s+4 t=-44} \\ {\text { 2) } 5 r \quad+4 t=-6}\end{array} \)
\( \begin{array}{lll}{1^{\prime}) -2)} & {r-8s} & {=-38} \\ {3) -2 r+5s} & {=21}\end{array} \)
I) \( 2 r-16 s=-76\)
II) \(-2 r+5 s=21\)
\(I+II) = -11 s = -55 \\ s = 5 \)
in 3) \(\begin{aligned} -2 r+5 s &=21 \\-2 r+2·5 &=21 \rightarrow r=2 \end{aligned}\)
in 1) \(\begin{aligned} 6-20+2 t &=-22 \\-14+2t &=-22 \quad-2 t=-4 \rightarrow t=-4 \end{aligned}\)
