Yesterday I went to the dentist's office to have a decayed tooth pulled out.

Remarks: I believe there should be only one decayed tooth. Just use or instead of one of them.

A dentist's office represents a dentist's office or clinic.

Due to the different educational background and work experience, the salary of employees is also very different.

The salary of employees depends on educational background and work experience.

Remarks: Dependence itself means "dependence", so the translation of "different" is repetitive.

The use of information technology can bring great progress to developing countries.

The application of information technology will lead to great progress in developing countries.

or

The application of information technology will lead developing countries to make great progress.

You solved the problem in the wrong way.

You are not dealing with the problem in the right way.

Deal with

Scientists believe that mankind is about to find an effective way to beat cancer.

Scientists believe that mankind is about to find an effective way to treat cancer.

Remarks: assume is more real, indicating the estimation and determination of the future.

Cancer should be plural, because it is not just a kind of cancer.

Divorce is not a joke.

Divorce cannot be taken lightly.

Believe me, this is the most authentic English translation!