Dell Inspiron 15 (7548, Late 2014) - Manual (Page 18)

Keyboard
Shortcut Keys
Mute audio
Decrease volume
Increase volume
Play previous track/chapter
Play/Pause
Play next track or chapter
Switch to external display
Search
Toggle keyboard backlight
Decrease brightness
Increase brightness
Toggle Fn‑key lock
Turn off/on wireless
Open application menu
Pause/Break
Toggle status light between hard‑drive
and battery‑status light
(Inspiron 7548 only)
System request
Toggle scroll lock
Sleep