Gene G. answered • 08/30/13

Tutor

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Retired Electrical Engineer Helping People Understand Math

Tami,

12=4(b-2)

Expand the right side using the distributive rule:

12=4b - 4*2

12=4b - 8

Add 8 to both sides:

12+8 = 4b - 8 + 8

20 = 4b

Divide both sides by 4:

20/4 = 4b / 4

5 = b

All you need to know is the distributive rule of multiplication:

a (b + c) = ab + ac

and when trying to isolate the variable you want solve for, whatever you do to one side of the equation, you must also do to the other side. That keeps both sides of the equation equal!

We did this by adding the 8 to move it to the other side, then dividing by 4 to make 4b become just b.

Hope this helps