Question

If $15\mathrm{x}+17\mathrm{y}=21$, $17\mathrm{x}+15\mathrm{y}=11$ .Then find the value of $\mathrm{x}-\mathrm{y}$.

Answer 1

Solve the given equations to find the required value

Let us consider the equations

$15\mathrm{x}+17\mathrm{y}=21$ $...\left(\mathrm{i}\right)$

$17\mathrm{x}+15\mathrm{y}=11$ $...\left(\mathrm{ii}\right)$

Subtracting equation $\left(\mathrm{i}\right)$ from equation $\left(\mathrm{ii}\right)$ we get

$2\mathrm{x}-2\mathrm{y}=-10$ $...\left(\mathrm{iii}\right)$

Dividing equation $\left(\mathrm{iii}\right)$ by $2$ we get

$\mathrm{x}-\mathrm{y}=-5$

Therefore, the value of $\mathrm{x}-\mathrm{y}$ is $-5$.