Question

Boris has 20 CDs in his music collection. Given that 20% of the CDs are rock music and 60 % of the CDs are pop music, how many CDs are other type of music? Show your work,

Answer 1

4 CDs are other types of music, because
20% of rock music is 4
60% of pop music is 16
20 - 16 - 4 = 4.