Complex sentence: Einstein used the experience he had gained during his years at the Swiss Patent Office to apply for valid patents for their inventions in several countries, the two eventually being granted 45 patents in their names for three different models.
Split into simpler sentences: Einstein used the experience he had gained during his years at the Swiss Patent Office to apply for valid patents for their inventions in several countries. The two were eventually granted 45 patents in their names for three different models.