Two types of music composition developed during the 20th century:
Rock-N-Roll - an evolution of rhythm and blues which relied heavily on electric instruments. Often dominated by heavy use of electric guitars in particular.
and Rap - a rhyming chant accompanied by rhythmic music. Often associated with derogatory lyrics and misogynistic undertones.
The human mind immediately may try to put them into categories or illustrate what they are about in their head.
Lowest number is 1 highest number is 9 so 9-1= 8. range is d. 8
