A couple that were just engaged decided to have their wedding in a hot air balloon. The biggest problem that the couple has is how many guests that they can invite.
There are three different types of hot air balloons that the aviation place allows for rent. The small hot air balloons cost 3 dollars and can hold 1 person, the medium cost 6 dollars and can hold 2 people, and the large cost 9 dollars and can hold 4 people.
There are 10 of each balloon type that are free on that day and the couple have a budget of $36. If the couple wants at least 2 of each type of balloon and will only get 2 large balloons, what is the maximum number of guests that they can invite?