+1253 Do you know how to distribute?
I think you do, or else you wouldn't get this problem.
Asinus got this correct with a well-thought out explanation, but just if you don't understand distributive, here I am.
3(4x-2y) means 3*4x+3*(-2y). We multiply the outside value, 3, by each term inside the parenthesis.
The equation then becomes \(12x-6y-6x-2y\)
6x-8y.
You are very welcome!
:P
+118608 Thanks Coolstuff, I like your explanation. 
Since you are interested in teaching I thought you might be interested in alternate techniques .
This is how I would do it if I was serioulsy teaching someone about expanding brackets.
I'd talk about the area of a rectangle. So a rectangle with sides 2 and 3 would have an area of 2*3 = 6
I'd draw that
Then I would move onto an algebraic example. I would start with one that only had plus signs but I have drawn a representation of the first half of this problem.
3(4x-2y)
So
\(3(4x-2y)\\=12x+-6y\\=12x-6y\)
