Let's denote the price of an adult ticket as \( x \). According to the problem, the price of a child ticket (for 12-and-under) is \( x - 2 \).
Maggie and her five friends (totaling 6 children) went to the movies, so the total number of tickets they bought is:
- 1 adult ticket
- 6 child tickets
The total cost of the tickets can be represented as:
\[ \text{Total Cost} = \text{Cost of Adult Ticket} + \text{Cost of 6 Child Tickets} \]
This can be written mathematically as:
\[ 30 = x + 6(x - 2) \]
Now, simplify the equation:
\[ 30 = x + 6x - 12 \] \[ 30 = 7x - 12 \] \[ 30 + 12 = 7x \] \[ 42 = 7x \] \[ x = 6 \]
Thus, the price of an adult ticket is \(\boxed{6}\).