Question 254333
You have two questions, but I am not sure of the second. 
2(3x+6)=7x 
step 1 - we have a BIG parenthesis. This means distributive property. We get
6x + 12 = 7x.
step 2 - we want to isolate the x, so we have to move the 6x part. WE do that by subtracting 6x from both sides to get
12 = x.
That is the answer.