$$$x^{10}y^8,\quad x^6y^3,\quad x^4y^3$\\\\ The highest power of x that is in all of them is $x^4$\\\\ The highest power of y that is in all of them is $y^3$\\\\ So the greatest common factor is $y^3x^4$\\\\$$
$$$x^{10}y^8,\quad x^6y^3,\quad x^4y^3$\\\\ The highest power of x that is in all of them is $x^4$\\\\ The highest power of y that is in all of them is $y^3$\\\\ So the greatest common factor is $y^3x^4$\\\\$$
