Josh and Alex work as design engineers creating high-end lighting fixtures. After one particularly enlightened afternoon, they decide to follow their dreams and open a cupcake bakery. Please sort their various costs, listed below, into the correct category.

Implicit Costs Not a Cost Explicit Costs
The garage space used for baking that can no longer be rented to a college student

Advertising space taken out on a social media network

Supplies like sugar, butter, and baking trays

The money they pay their neighbor's six year old son to deliver cupcakes to their customers

The salary Alex earned in his previous job designing light fixtures