A group of seven adults went to the movies. The total cost of the movie tickets was $30. This doesn't seem possible, does it? After all, 30 is not evenly divisible by 7. Ah, but there's a hitch. The reason that $30 was the total cost was that some members of the group were senior citizens, so they got to see the movie at half price. How many of the group were senior citizens, and how much did the tickets cost?