Tactics: Logical thinking

Among the many important tactical thought processes is that called logical thinking. The thought process is as follows:

(1) Come up with idea -> (2) It doesn't work, figure why it does not work -> (3) eliminate reason why it does not work -> (4) success

Let's see this in action with an example:

The problem is not excessively difficult, but is mainly to illustrate the thought process. The thought process here was:

(1) Calculate ...Qa5+  (2) This almost works, but it does not work because the bishop on g5 is defended (3) Solve this problem by first removing the defender of g5

Did that make sense?

Let's see if you can apply what we have learned to the following exercise: