530. а)q = 1 - 7/12 = 5/12 б)q = 1 - 4/15 = 11/15 в)q = 1 - 7/16 = 9/16 г)q = 1 - 13/21 = 8/21

536. 1/4 ч = 60/4 = 15 минут

5/12 ч = 60* 5/12 = 25 минут

1/3 ч = 60/3 = 20 минут

15+25+20= 60 минут = 1 час

538. а) 2 4/13 + 2/13 = 30/13 + 2/13 = 32/13 = 2 6/13 б) 2 4/13 + 1 2/13 = 30/13 + 15/13 = 45/13 = 3 6/13 в) 2 4/13 + 10/13 = 30/13 + 10/13 = 40/13 = 3 1/13 г) 2 4/13 + 1 10/13 = 30/13 + 23/13 = 53/13 = 4 1/13

539. а) 1 1/8 + 3/8 = 9/8 + 3/8 = 12/8 = 6/4 = 3/2 = 1 1/2 б) 1 1/8 + 2 3/8 = 9/8 + 19/8 = 28/8 = 14/4 = 7/2 = 3 1/2 в)1 1/8 + 7/8 = 9/8 + 7/8 = 16/8 = 2 г)1 1/8 + 2 7/8 = 9/8 + 23/8 = 32/8 = 4