Question

pleazzz help me! it's too difficult for me​

Answer 1

$\mathrm{ Since} \: x= \frac{D_x}{D}, \\ \mathrm{we \: have} \frac{3-12a}{-7}=x=3 \\ \implies 3-12a=-21\\ \implies 12a=24 \\ \implies \textcolor {red}{\boxed{a=2}}\\ \mathrm{Now,} \\ y=\frac{D_y}{D}=-2\\ \mathrm{Thus} \frac{12+b}{-7}=y=-2\\ \implies 12+b=14 \\ \mathrm{So} \: \textcolor {red} {\boxed{b=2}}$