Question

For what value of b does

Answer 1

There's no solution.

Answer 2

There is no solution because the result on the left hand side is 12² since the b terms cancel out, and 12² is not equal to 12.
Note that (1/12)^-2b is the same as 12^2b. When we add the exponents we get 2b-2b+2=2, hence 12² on the left.