числитель:

1) 0,9 - 1/3 + 0,75 - 1/15 = (0,9 + 0,75) - (1/3 + 1/15) = 1,65 - (5/15 + 1/15) =

  = 1,65 - 6/15 = 1,65 - 0,4 = 1,25,

2) 0,5 - 1/6 = 5/10 - 1/6 = 15/30 - 5/30 = 10/30 = 1/3,

3) 1,25 : 1/3 = 125/100 * 3 = 375/100 = 3,75,

4) 3,75 : 5/12 = 375/100 * 12/5 = 9,

знаменатель:

5) 5/7 - 0,4 + 11/14 = 5/7 - 4/10 + 11/14 = 50/70 - 28/70 + 55/70 = 77/70 =

  = 11/10 = 1 1/10  (или 1,1),

6) 2/3 + 0,8 - 7/15 = 2/3 + 8/10 - 7/15 = 20/30 + 24/30 - 14/30 = 30/30 = 1,

7) 1,1 : 1 = 1,1,

8) 1,1 : 2 1/5 = 11/10 : 11/5 = 11/10 * 5/11 = 5/10 = 1/2  (или 0,5),

9) 9 : 0,5 = 18,

ответ:   18

0,9-1/3=9/10-1/3=27/30-10/30=17/30

17/30+0,75=17/30+3/4=34/60+45/60=79/60

79/60-1/15=79/60-4/60=75/60=5/4

0,5-1/6=1/2-1/6=3/6-1/6=2/6=1/3

5/4:1/3=5/4*3=15/4

15/4:5/12=15/4*12/5=9

5/7-0,4=5/7-2/5=25/35-14/35=11/35

11/35+11/14=22/70+55/70=77/70=11/10

2/3+0,8=2/3+4/5=10/15+12/15=22/15

22/15-7/15=15/15=1

11/10:1=11/10

11/10:2 1/5=11/10*5/11=1/2

9:1/2=9*2=18