The principle means repeating some of the aspects of a design throughout the entire presentation. It would also help to organize information that would guide readers. Examples would be using a template,same font size and type,font colour and color scheme.
He took exactly four years
We're is the contraction for we are
I believe the answer is monophonic
49*12 = 50*12-12
because 49*12 = 588 and 50*12-12 = 588