I don't get it help me quick

When you are making a circle graph by hand, how do you convert a number for a part into its corresponding angle measure in the circle graph? when you are making a circle graph by hand, what should you do if one of your angle measures is greater than 180°?

Henry is an avid reader, he devours 90 pages in half an hour how many pages has henry read per minute?

In the diagram, ab is tangent to c, ab = 4 inches, and ad = 2 inches. find the radius of the circle.