There are 7 streets to be named after 7 tree types. Ash, Cedar, Elm, Maple, Pine, Spruce, and Willow.
A city planner randomly selects the street names from the list of tree types.
Compute the probability of each of the following events.

Event A: The first street is Ash, followed by Elm and then Maple.

Event B: The first three streets are Elm, Spruce, and Pine, without regard to order.

Write your answers as fractions in simplest form.