Anyone? i know it's an octagon but from there i'm stuck

Meghan has created a diagram of her city with her house, school, store, and gym identified. a. how far is it from the gym to the store? b. meghan also wants to walk to get some exercise, rather than going to the gym. she decides to walk along arc ab. how far will she walk? round to 3 decimal places.

Im so bad at fractions they are not my best math thing to work on

Michael and imani go out to eat for lunch if their food and beverages cost 25.30 and there is an 8% meals tax how much is the bill