Question

If $12x+17y=48$ and $17x+12y=68$, then find $x-y$.

Answer 1

Given

$12x+17y=\mathrm{48.....}\times 12$

$17x+12y=\mathrm{68.....}\times 17$

$144x+204y=576$

$289x+204y=1156$

$-145x=-580$

$x=4$

substitute $x$ value in the 1st equation

$12\times 4+17y=48$

$48+17y=48$

$17y=0$

then

$x-y=4-0=4$