13+(     )=16

(     )-9=8

9+(     )=20

(     )-11=9

(     )+2=18

(     )+7=11

(     )-3=9

(     )+0=13

(     )+13=17

15+(     )=17

18-(     )=0

18-(     )=11

15-(     )=1

(     )-6=8

15+(     )=18

(     )-12=5

18-(     )=17

(     )+0=17

11-(     )=4

(     )+15=20

(     )-9=5

(     )-5=8

(     )-16=0

(     )+0=15

20-(     )=3

12-(     )=1

(     )+1=19

13-(     )=6

17-(     )=9

(     )-19=0

(     )-12=8

19+(     )=19

(     )-12=4

(     )+2=18

(     )-0=12

(     )+7=16

14+(     )=17

2+(     )=12

4+(     )=17

(     )-15=1

(     )+12=19

(     )+9=17

16+(     )=16

14-(     )=9

(     )+15=17

(     )+1=13

9+(     )=20

0+(     )=16

(     )+11=19

15-(     )=11