2 Elements:
Color is being used in cooperation with Line to make colors "pop" more. Along with this, it provides and organized, yet visually appealing aesthetic to the art piece.
Color in particular, is what separates the work into sections that draw the viewer's eyes in, due to the contrast choices by the artist.
While Line, physically separates the colors, but provides the attractive composition.
(I would answer principles too, but I don't have the time currently;; Hopefully this helps though.)
13.9
Explanation: add the amount he doesn’t in gift A (10.7) and the amount he spent on part B (5.4) and you get 16.1. The. Subtract 16.1 from 30 and you get 13.9
He incorporated stage-like settings
the answer is H.............