2/9 •(3/10•7/8); (10/13•11/12)•(12/55•13/20).

   2/9 *(3/10 * 7/8) = 1/3 * 1/5 * 7/8 = 7/120   (10/13 *11/12)*(12/55 *13/20) = 10/13 *13/20 *11/12 *12/55 == 1/2 *1/5 =1/10 = 0,1