The questions are in two scenarios:
1. Zaid is fundraising for a masjid. The masjid tells him you get $1,000 for fundraising and 10% of how much he raises. He raises 100,000 so he gets $11,000
2. Zaid is fundraising for a masjid. The masjid tells him you get 10% of how much you raise. He raises 100,000 so he gets $10,000.
Are any of these scenarios above permissible, and why?
بِسْمِ اللهِ الرَّحْمنِ الرَّحِيْم
In the name of Allah, the Most Gracious, the Most Merciful
Both scenarios are permissible as he is working as an agent (wakīl) on behalf of the masjid (in order to conduct the fundraising and to generate the money for the ones who have appointed him to carry out this task).
Only Allah knows best
Written by Shaykh Tahsin Alam
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
 Al-Marghīnānī, al-Hidāyah, volume 5 pg. 398