Answer :
[tex]D+R+C=1075\\D=3R\\C=R+105\\\\(3R)+R+(R+105)=1075\\5R=970\\R=194\\\\D=3(194)=\\D=582\\\\C=(196)+105=\\C=301[/tex]
582 dance songs.
194 rock songs.
301 country songs.
582 dance songs.
194 rock songs.
301 country songs.