б)2 3/4:(1 1/2-2/5) = 2 3/4 : (3/2 - 2/5) = 11/4 : (11/5) = 11/4 5/11 = 5/4(3/4+5/6) : 3 1/6 = (9/12 + 10/12) : (19/6) = 19/12 : 19/6 = 19/12 6/19 = 1/2
Итого: 5/4 + 1/2 = 5/4 + 2/4 = 7/4 = 1 3/4
в)(2/15 + 7/12) 30/43 - 2 : 2 1/2 5/32 = (8/60 + 35/60) 30/43 - 2/5 5/32 = 43/60 30/43 - 2/5 5/32 = 1 - 1/4 = 3/4
г)(3 1/2 : 4 2/3 + 4 2/3 : 3 1/2) 4 4/5 = (7/2 : 14/3 + 14/3 : 7/2) 24/5 = (7/2 3/14 + 14/3 2/7) 24/5 = (3/4 + 4/3) 24/5 = (9/12 + 16/12) 24/5 = 25/12 24/5 = 5/3 * 24/5 = 8
Итак:б) 1 3/4в) 3/4г) 8
б)
2 3/4:(1 1/2-2/5) = 2 3/4 : (3/2 - 2/5) = 11/4 : (11/5) = 11/4 5/11 = 5/4
(3/4+5/6) : 3 1/6 = (9/12 + 10/12) : (19/6) = 19/12 : 19/6 = 19/12 6/19 = 1/2
Итого: 5/4 + 1/2 = 5/4 + 2/4 = 7/4 = 1 3/4
в)
(2/15 + 7/12) 30/43 - 2 : 2 1/2 5/32 = (8/60 + 35/60) 30/43 - 2/5 5/32 = 43/60 30/43 - 2/5 5/32 = 1 - 1/4 = 3/4
г)
(3 1/2 : 4 2/3 + 4 2/3 : 3 1/2) 4 4/5 = (7/2 : 14/3 + 14/3 : 7/2) 24/5 = (7/2 3/14 + 14/3 2/7) 24/5 = (3/4 + 4/3) 24/5 = (9/12 + 16/12) 24/5 = 25/12 24/5 = 5/3 * 24/5 = 8
Итак:
б) 1 3/4
в) 3/4
г) 8