How do we solve questions (a) and (b)?

Consider the following puzzle. Five coins are arranged around the vertices of a pentagon. The goal for this puzzle is to go from the starting configuration below to a goal configuration that is a rearrangement of the coins around the pentagon. There are two allowable moves that can be applied repeatedly in any order: - Move X: you can rotate the coins around the pentagon, and - Move Y: you can rotate the coins in the upper triangle of the pentagon. For example, two applications of move X from the starting position results in Then one application of move Y to the above results in For each of the following, show that the given configuration can be obtained with a combination of moves X and Y, or prove no combination of moves X and Y lead to the given configuration: (a) (b)