31 + 48 =

(a)  

29 + 39 =

(a)  

54 + 14 =

(a)  

90 - 72 =

(a)  

89 - 59 =

(a)  

81 - 46 =

(a)  

75 - 50 =

(a)  

1 x 2 =

(a)  

2 x 3 =

(a)  

3 x 4 =

(a)  

4 x 5 =

(a)  

5 x 6 =

(a)  

6 x 7 =

(a)  

7 x 8 =

(a)  

8 x 9 =

(a)  

9 x 10 =

(a)  

10 x 11 =

(a)  

3 : 1 =

(a)  

8 : 2 =

(a)  

15 : 3 =

(a)  

24 : 4 =

(a)  

35 : 5 =

(a)  

48 : 6 =

(a)  

63 : 7 =

(a)  

48 : 8 =

(a)  

45 : 9 =

(a)  

70 : 10 =

(a)  

99 : 11 =

(a)