Let the number of adult tickets sold be \( x \). Then, the number of student tickets sold can be expressed as \( x + 25 \) (since the class sold 25 more student tickets than adult tickets).
The total revenue from ticket sales can be expressed with the following equation:
\[ 6x + 3(x + 25) = 660 \]
Now, we can simplify and solve this equation step by step:
- Distribute the \( 3 \) in the equation:
\[ 6x + 3x + 75 = 660 \]
- Combine like terms:
\[ 9x + 75 = 660 \]
- Subtract \( 75 \) from both sides:
\[ 9x = 660 - 75 \] \[ 9x = 585 \]
- Divide both sides by \( 9 \):
\[ x = \frac{585}{9} \] \[ x = 65 \]
Now that we have \( x \), the number of adult tickets sold, we can find the number of student tickets sold:
\[ x + 25 = 65 + 25 = 90 \]
Therefore, the drama class sold 90 student tickets.