№1
27/36 = (27 : 9)/(36:9) = 3/4
50/75 = (50 :25)/(75:25) = 2/3
112/80 = (112 : 16) /(80:16) = 7/5
№2
5/14 = 15/42 ; 8/21 = 16/42 ; 15/42<16/42 ⇒ 5/14 < 8/21<br>31/88 = 93/264; 25/66 = 100/264 ; 93/264< 100/264 ⇒ 31/88<25/66<br>
№3
13/18 + 7/12 = (13*2 + 7*3)/36 = 47/36 = 1 ц. 11/36
5/7 - 3/5 = (5*5 - 3*7)/35 = 4/35
5/6 - 3/8 - 1/12 = (5*4 - 3*3 - 1*2) /24 = 9/24 = 3/8
№4
1) 3/8 - 1/6 = (3*3 - 1*4)/24 = 5/24 пути прошел поезд во II сутки
2) 3/8 + 5/24 = (3*3 + 5)/24 = 14/24 = 7/12
Ответ: 7/12 пути прошел поезд за двое суток.
№5
7/9 = 21/27
8/9 = 24/27
7/9 < 22/27 < 8/9
7/9 < 23/27 < 8/9
Ответ : 22/27 ; 23/27 .