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2013-03-22T08:17:06+01:00

5b+7=12

5b= 5

b= 5/5 = 1

 

8+4b=20

4b=12

b=12/4 =3

 

31=3+7b

28=7b

28/7 = b

b=4

 

2b+11=11

2b=0

b=0