Выполните вычитание: 1) 3 1/12 - 1/6; 2) 8 7/30 - 2 9/20; 3) 7 10/51 - 4 21/34; 4) 5 1/4 - 1 3/8.

1) 3 1/12 - 1/6 = 3 1/12 - 2/12 = (37-2)/12=35/12 = 2 11/12; 2) 8 7/30 - 2 9/20 = 6 7/30 - 9/20 = 187/30 - 9/20=(187*2-9*3)/60=(374-27)/60=347/60=5 47/60; 3) 7 10/51 - 4 21/34=3 10/51 - 21/34=3 20/102 - 63/102=2 122/102-63/102=2 59/102; 4) 5 1/4 - 1 3/8 = 4 1/4 - 3/8 = 4 2/8 - 3/8 = 3 10/8 - 3/8 = 3 7/8.