2.

а) 17/30 и 21/40, 17/30 = 68/120, 21/40 = 63/120

68/120 >  63/120, значит 17/30 >   21/40

б) 8,702603 > 8,7020603

в) 93/96 и 23/24, 23/24 = 92/96

93/96 >  92/96, значит 93/96   > 23/24

г) -11,02 = -11,0200

3.

а) к1 = 19/24,  к2 = 20/24

б) n1 = 5/12, n2 = 6/12,  n3 = 7/12

4.

11/18 = 0,6(1)