Question

A DJ has a total of 1075 dance, rock, and country songs on her system. The dance selection is three times the size of the rock selection. The country selection has 105 more songs than the rock selection. How many songs on the system are dance? Rock? Country?
Please help! This has to do with substituting linear equations.

Answer 1

$D+R+C=1075\\D=3R\\C=R+105\\\\(3R)+R+(R+105)=1075\\5R=970\\R=194\\\\D=3(194)=\\D=582\\\\C=(196)+105=\\C=301$

582 dance songs.
194 rock songs.
301 country songs.