ALSO HELP WITH THIS :)

Find the greatest common factor of the followig monomials 21u^5v,3u^4v^6, and 3u^2v^5

The art class is planning to paint a mural on an outside wall. this figure is a scale drawing of the wall. width: 11 in length: 28 in unit rate: 1.5 ft per in. write the ratio of the area of the drawing to the area of the actual mural. write your answer as a unit rate. show that this unit rate is equal to the square of the unit rate 1.5 ft per in

Yvaries inversely as x. y =12 when x=5. find y when x=4