Show:
Adding
Adding
Subtracting
Subtracting
Adding & Subtracting
100

20 + 15

35

100

13 + 2

15

100

30 - 12

18

100

21 - 20

1

100

12 + 3 

15

200

100 + 34

134

200

20 + 9

29

200

12 - 6

6

200

23 - 23

0

200

12 -1

11

300

17 + 30

47

300

13 + 3

16

300

17 - 13

4

300

13 - 4

9

300

10 - 7

3
400

24 + 10

34

400

12 + 1

13

400

100 - 50

50

400

11 - 10

1

400

12 - 5

7

500

50 + 11

61

500

15 + 2

17

500

23 - 13

10

500

17 - 7

10

500

12 + 4

16