Find a positive angle less than 360° that is coterminal with the angle -240°

Hello i need some with trigonometric substitutions. [tex]\int\limits^a_b {x} \, dx[/tex]

There are 15 plates and each plate is either 7 or 12 inches diameter. which systems of equations do you use to find the number of 7 inch plates, x and 12 inch plates, y

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