Đáp án: $y=-120, x=570$
Giải thích các bước giải:
Ta có: $x+y=450\to y=450-x$
Mà $\dfrac1{19}\cdot 3x+\dfrac{1}{10}\cdot 5y=30$
$\to \dfrac1{19}\cdot 3x+\dfrac{1}{2}\cdot y=30$
$\to \dfrac1{19}\cdot 3x+\dfrac{1}{2}\cdot (450-x)=30$
$\to \dfrac{3}{19}x\cdot \:38+\dfrac{1}{2}\left(450-x\right)\cdot \:38=30\cdot \:38$
$\to 6x+19\left(450-x\right)=1140$
$\to -13x+8550=1140$
$\to x=570$
$\to y=450-570=-120$
