The angles of a quadrilateral are x∘,(x−10)∘,(x+30)∘ and (2x)∘. Find the value of the greatest angle.
If (2x+5)∘, 3x∘, (5x+15)∘and 40∘ are four angles of a quadrilateral, find the value of ∠x and hence find the four angles. [2 MARKS]