Let K be the number of songs on Kelly's music player,
L be the number of songs on Lou's music player and T be the number of songs on Tiffany's music player.
We know that,
K = 4*L
and
T = 6*L
and also
K + T + L = 682
Then,
4*L + 6*L + L = 682
11L = 682
L = 62
From here we know that
T = 6*62 = 372
K = 4*62 = 248
So Kelly has 248 songs on her music player