Answers:
12. 2 3/5+1 4/6 = (2+1)+(3/5+4/6) = 3+19/15 = 64/15
13. 2/4*4/6 = 8/24 = 1/3
14. 3/4*3/6 = 9/24 = 3/8
15. 2/6*4/6 = 8/36 = 2/9
16. 2/4*1/6 = 2/24 = 1/12
17. 3/4/1/6 = 18/4 = 9/2
18. 3/4/2/4 = 12/8 = 3/2
19. 3/6/4/6 = 18/24 = 3/4
20. 5/7+2/7 = 7/7 = 1
21. 4/5+5/7 = 53/35
22. 3/5+5/5 = 8/5
23. 1/6-1/6 = 0
24. 3/7-2/3 = -5/21
25. 3/5-2/7 = 11/35
