Three Languages on a Plane

Difficulty: Hard · Topics: Discrete Mathematics, Sets, Word Problems

All 26 people on a plane know at least one of English, French and German. Everyone on this plane who knows German also knows English, and 2 people speak all three languages.

The number of people who know only English is 7 more than the number of people who know only French, and the number of people who know English and French is 3 more than the number of people who know English and German.

How many people on this plane know French?