1.
А) 3/20 + 1/5 - 1/6 = 9/60 + 12/60 - 10/60 = 11/60
Б) 3/4 - 4/25 - 7/20 = 75/100 - 16/100 - 35/100 =
= 24/100 = 6/25
В) 3/7 - 1/6 + 5/14 = 18/42 - 7/42 + 15/42 =
= 26/42 = 13/21б
2.
А) 3/7 + 4/9 + 4/7 + 5/9 =
= 3/7 + 4/7 + 4/9 + 5/9 = 7/7 + 9/9= 1 + 1 = 2
Б) 1/11 + 1/5 + 4/11 + 4/5 + 6/11 =
= 1/11 + 4/11 + 6/11 + 1/5 + 4/5 = 11/11 + 5/5 = 1+1 = 2
В) 1/15 + 4/15 + 1/18 + 5/18 + 2/21 + 5/21 + 1/24 + 7/24 =
= 5/15 + 6/18 + 7/21 + 8/24 =
= 1/3 + 1/3 + 1/3 + 1/3 = 4/3 = 1 целая 1/3
Г) 1/8 + 1/12 + 1/16 + 1/20 + 3/8 + 5/12 + 7/16 + 9/20=
= 1/8 + 3/8 + 1/12 + 5/12 + 1/16 + 7/16 + 1/20 + 9/20=
= 4/8 + 6/12 + 8/16 + 10/20 =
= 1/2 + 1/2 + 1/2 + 1/2 = 4/2 = 2