Can someone help me with this? its kinda confusing geometry

Pete is making decorations for a dinner party. the instructions tell him to use 9 flowers for a medium-sized decoration. complete each statement to adjust the flowers for different-sized decorations based on these instructions.

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

The collection of beautiful oil paintings currently on display at an art gallery well defined; set not well defined; not a set