Вычислить: а) 7\16+1\4; б) 25\36-2\9; в) 7\12-5\24; г) 5\7-11\21; д) 1\6+5\18;

Приведем дроби к одному знаменателю и вычислим.

а) 7/16 + 1/4 = 7/16 + (1 * 4)/16 = 7/16 + 4/16 = (7 + 4)/16 = 11/16.

б) 25/36 - 2/9 = 25/36 - (2 * 4)/36 = 25/36 - 8/36 = (25 - 8)/36 = 17/36.

в) 7/12 - 5/24 = (7 * 2)/24 - 5/24 = 14/24 - 5/24 = (14 - 5)/24 = 9/24 = 3/8.

г) 5/7 - 11/21 = (5 * 3)/21 - 11/21 = 15/21 - 11/21 = (15 - 11)/21 = 4/21.

д) 1/6 + 5/18 = (1 * 3)/18 + 5/18 = 3/18 + 5/18 = (3 + 5)/18 = 8/18.

е) 19/45 + 4/15 = 19/45 + (4 * 3)/45 = 19/45 + 12/45 = (19 + 12)/45 = 31/45.

ж) 15/16 - 3/32 = (15 * 2)/32 - 3/32 = 30/32 - 3/32 = (30 - 3)/32 = 27/32.

з) 7/15 + 1/3 = 7/15 + (1 * 5)/15 = 7/15 + 5/15 = (7 + 5)/15 = 12/15 = 4/5.

и) 11/13 - 20/39 = (11 * 3)/39 - 20/39 = 33/39 - 20/39 = (33 - 20)/39 = 13/39 = 1/3.

к) 3/50 + 18/25 = 3/50 + (18 * 2)/50 = 3/50 + 36/50 = (3 + 36)/50 = 39/50.

л) 45/62 - 10/31 = 45/62 - (10 * 2)/62 = 45/62 - 20/62 = (45 - 20)/62 = 25/62.

м) 29/64 + 3/8 = 29/64 + (3 * 8)/64 = 29/64 + 24/64 = (29 + 24)/64 = 53/64.