Batman: Arkham City Riddlers 4th Hostage (Intellectual Achievement)

Here's how to solve Riddler' 4th Hostage puzzle and get the Intellectual Achievement!
1st hostage- 0 secrets
2nd hostage- 80 secrets
3rd hostage- 160 secrets
4th hostage- 240 secrets
5th hostage- 320 secrets
Final Hideout- 400 secrets