Tentukan nilai x dan y menggunak sistem eliminasi dan subtitusi A. 8x + 9y=55 dan 7x + 4y=27 B. 2x + 5y= 25 dan 5x + 2y=29

[tex]\displaystyle 8x+9y=55|\times7|56x+63y=385\\\underline{7x+4y=27|\times8|56x+32y=216}-\\~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~31y=169\\~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~y=\frac{169}{31}\\\\7x+4y=27\\7x+4\cdot\frac{169}{31}=27\\7x=27-4\cdot\frac{169}{31}\\7x=\frac{837-676}{31}\\7x=\frac{161}{31}\\x=\frac{23}{31}\\\\\boxed{\boxed{\text{HP}=\left\{\frac{23}{31};\frac{169}{31}\right\}}}[/tex]

[tex]\displaystyle 2x+5y=25|\times5|10x+25y=125\\\underline{5x+2y=29|\times2|10x+4y=58}-\\~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~21y=67\\~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~y=\frac{67}{21}\\\\5x+2y=29\\5x+2\cdot\frac{67}{21}=29\\5x=29-2\cdot\frac{67}{21}\\5x=\frac{609-134}{21}\\5x=\frac{475}{21}\\x=\frac{95}{21}\\\\\boxed{\boxed{\text{HP}=\left\{\frac{95}{21};\frac{67}{21}\right\}}}[/tex]