3-3k/9k

-2kbc/3a-9

21/a²

2/5c⁴

7-7n/n

-p/5p+15

-2/mb-4b

1/3b+3c

3/x-y

2k²-12kp+18p²/9k²p

ax²-2axy+ay²/c²dx+c²dy

10a/9b

21b/8c

35c/80d

15d²/110e

9/1

6k/7k

-3/-2

48/7 bn

2xb/cy

ap/3dm

3a/2p

2x/3y

10y/-21a

10c³e/21ax²