"Is František your uncle?"

Translation: František je tvůj strýc?

[mkling21]

wouldn't strejda also be correct?

[endless_sleeper]

Strejda is very colloquial. We aim to teach Standard Czech.

[Holandsky_Honza]

My thought also: "František je tvoje strejda?"

[endless_sleeper]

Strejda is masculine animate, therefore the correct adjectival form is tvůj.

[Christine_nl]

Isn't František the subject?

[kacenka9]

i believe so