Question

Solve 31x+23y=39 23x+31y=15

Answer 1

31x+23y=39..............................1)
23x+31y=15..............................2)

1)*23 & 2)*31 →

713x+529y=897
713x+961y=465
-        -         -
-------------------------
-432y  =432
∴y= -1
23x+31y=15
∴23x+31*(-1)=15
or,23x=15+31=46
∴x=2
∴x=2,y=-1.