الافضل اقول
How long will you spend there and with who?i
ولا
How long will you spend there and with whom?i
الافضل اية ولية
وادى الجملة اللى عملنا عليهم الاسئلة دى
I will spend a week with my brother who works at a company

الجمله الثانية أفضل والله أعلم

How long will you spend there and with whom? is the correct question