Question

Выполните действия: (x-5)(5+x);
(8+y)(y-8);
(10-k)(k+10);
(a+2/4b)(a-2/3b);
(4/9x-y)(y+4/9x);
(4/15n-m)(m+4/15n);
(9x-5y)(9x+5y);
(-4a+3b)(3b+4a);
(13k-2d)(2d+13k);
(5/4c+3/7d)(3/7d-5/4c);
(1/3x-3y)(3y+1/3x);
(1/5a+1/9b)(1/9b-1/5a).