How to use distributive property to find 12 + 20 ?

The distributive property states that  

a*(b + c) = a*b + a*c  

You can use the distributive property in reverse to factor out a common factor from the sum of 2 numbers.  If you realize that 12 = 4*3 and 20 = 4*5 then you can write  

12 + 20 = 4*3 + 4*5 = 4*(3 + 5)

1. 3.4/4

2. 0.8/7

3. 0.5 x 3

4. 0.9 x 6

5. 10.8

6. 2.35

7. 0.567

8. 9.35

9. 0.02

10. 0.06

11. 0.16

12. 0.42

13. 0.63

14. 5.6

15. 8.1

16. 9.9

17. 0.28

18. 0.48

19. 0.27

20. 0.49

21. 0.45

22. 0.72

23. 0.9

24. 0.88

25. 0.75

26. 0.16

27. 0.328

28. 0.495

29. 0.72

30. 1.068

the arc length is found by finding the circumference of the full circle (2xpixradius) and then dividing by 4 to find just one quarter of the circle (90 degrees).