1. 6/16 = 3/8
9/45 = 1/5
32/88 = 4/11
36*14/7*12 = 3*2/1*1= 6
2. a) 7/18 и 5/12 б) 11/36 и 13/48
14/36 < 15/36 44/144 > 39/144
3. а) 3/8 + 7/16 = 6/16 + 7/16 = 13/16
б) 7/15 - 3/20 = 28/60 - 9/60 = 19/60
в) 23/40 - 9/20 + 1/16 = 46/80 - 36/80 + 5/80 = 15/80 = 3/16
4. a) 7/13 - a = 7/26 б) 4,72c + 2,8c = 78,96
-a = 7/26 - 7/13 7,52c = 78,96
-a = 7/26 - 14/26 c = 10,5
-a = -7/26
a = 7/26
5. общий знаменатель - 72
1) 21/72 + 4/72 = 25/72 (т.) - продали во второй день
2) 21/72 + 25/72 = 46/72 = 23/36 (т.) - продали в оба дня
Ответ: 23/36 (т.)