Why only 775 ???
if you want to know why only 775 here's your answer
Numeric permissions can Solve your problem.
sudo chmod 775 'your directory' 
Most of you guys like to know why always developer use chmod 775 to manage permission issue.
- 400 read by owner
- 040 read by group -
- 004 read by anybody
- 200 write by owner
- 020 write by group
- 002 write by anybody
100 execute by owner 010 execute by group
- 001 execute by anybody
400 +040 +004 +200 +020 +100 +010 +001 =775
This will give permission, but cannot write by anybody.
