Question 470933
using Cramer's rules {{{x=det(A1)/det(A)}}}, {{{y=det(A2)/det(A)}}}, 
{{{det(A)=abs(matrix(2,2,1,2,3,-4))=1*(-4)-2*3=-10}}}
{{{det(A1)=abs(matrix(2,2,7,2,-9,-4))=7*(-4)-2*(-9)=-10}}}
{{{det(A2)=abs(matrix(2,2,1,7,3,-9))=1*(-9)-7*3=-30}}}
{{{x=(-10)/(-10)=1}}}, {{{y=(-30)/(-10)=3}}}, 
Answer (1,3)