Pretty easy.

Listen in class, if your teacher is boring, tell him/her.

10 years ago. Rating: 6
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  6  + 2b    =   15 + 5b

- 15 - 2b  =  - 15  - 2b

________________________________

-9   =   3b

___     ____

 3          3

-3 = b

10 years ago. Rating: 5
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6+2b=15+5b

You want to get "like" terms on the same side of the equals sign.  
6 + 2b   - 6 = 15 + 5b - 6   (What I do on one side of the equals sign I must do on the other to keep them equal.  

If I subtract 6 from the left, I subtract it from the right.  Now, on the left, I have only 2b.  On the right, I have 9 (15 - 6) + 5b

Now, let's get the "b" together on the OPPOSITE side of the 9.  I have to subtract 5b from BOTH sides.  2b - 5b = 9 + 5b - 5b

NOW, i have -3b = 9
To find out what "b" is, I must finally divide by 3.  I'll have to divide 9 by 3, too, to keep my equation in balance:   -3b/3 = 9/3  

-b = 3, b = -3.    Plug in -3 where "b" is and see if you're right!  

6 + 2(-3) = 15 + 5(-3)  
6 + (-6) = 15 + (-15)

0 = 0     Looks like we got it right!   :D

10 years ago. Rating: 4
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6+2b = 15+5b 

2 1/2  (6+2b) = 15+5b 

Just 2 1/2

10 years ago. Rating: 2
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