17-(     )=16

12-(     )=12

17-(     )=15

12-(     )=6

15-(     )=10

20-(     )=8

11-(     )=7

12-(     )=11

17-(     )=16

19-(     )=16

17-(     )=13

15-(     )=1

11-(     )=6

19-(     )=6

15-(     )=11

14-(     )=2

17-(     )=1

13-(     )=11

19-(     )=18

19-(     )=13

16-(     )=13

12-(     )=12

13-(     )=5

16-(     )=3

20-(     )=13

20-(     )=13

11-(     )=9

16-(     )=1

12-(     )=12

12-(     )=9

18-(     )=9

12-(     )=6

15-(     )=1

13-(     )=5

20-(     )=4

14-(     )=14

18-(     )=16

20-(     )=19

17-(     )=6

13-(     )=12

19-(     )=9

12-(     )=7

15-(     )=1

17-(     )=3

15-(     )=14

16-(     )=1

12-(     )=4

13-(     )=3

20-(     )=14

16-(     )=11