Please can someone help me I’m confused and lost

Brainlest answer can you find the area and circumference of a circle given the radius or diameter? if its yes or no explain why

Geometry in the diagram, ∠abc is a right angle. ∠dbc = 30°27'40". find the measure of ∠abd.

In a small section of a stadium there are 40 spectators watching a game between the cook islands and fiji. they all support at least one of the two teams. 25 spectators support the cook islands and 16 of these support both teams. how many support only fiji?