Question

Solve for $x$ and $y$:

$2x+4y=9$

$4x+y=4$

Answer 1

$2x+4y=\mathrm{9....}\left(i\right)$

$4x+y=\mathrm{4....}\left(ii\right)$

$⟹y=4-4x.....\left(iii\right)$

Put in $\left(i\right)$

$\Rightarrow 2x+4(4-4x)=9$

$\Rightarrow 2x+16-16x=9$

$\Rightarrow -14x=9-16$

$\therefore x=\frac{-7}{-14}=\frac{1}{2}$

Put in $\left(iii\right)$

$\Rightarrow y=4-4\left(\frac{1}{2}\right)$

$\therefore y=2$