Is the following an identity or have no solution. 2 (a-4) = 4a - (2a+4)

You multiply everything in the parenthesis by the number outside.

In this case its 2 and - 1. the first part is 2a-8 the second part is 4a - 2a+16a

so it looks like this 2a-8=4a-2a+16a.

combine like terms and get 2a-8=18a.

Subtract the other 2a from the other side and you have 8=16a

divide each side by 16 and you have 8/16 which is one half.

This equation is invalid, the left and right sides are not equal, therefore there is no solution.