Find two solutions of the following equations:

$x+y=7$

Find two solutions of the following equations:

$y=6x$

Find two solutions of the following equations:

$x-3y=6$

Find two solutions of the following equations:

$x+2y-4=0$

Find two solutions of the following equations:

$2x+4y-12=0$

Find two solutions of the following equations:

$2x-y+3=0$

Write the following equation in the form $ax+by+c=0$ and find values of $a,b$ and $c$.

$4=3x-5y$

Check whether $(1,-1)$ and $\left(\mathrm{3,1}\right)$ are solutions of this equation or not.