a) 9|17 * 13|5 * 17|9 * 5|13=
б) (-11/37) * (-5/14) * (37/11) * (-28)

а) 9/17 * 13/5 * 17/9 * 5/13 = (9/17 * 17/9) * (13/5 * 5/13) = 1 * 1 = 1б) (-11/37) * (-5/14) * (37/11) * (-28) = ((-11/37) * (37/11)) * ((-5/14 * (-28)) = - 1 * 10 = - 10