Answer:
The number of adult tickets sold was 121
Explanation:
The general equation is: S + A = T ;where S means student tickets, A means adult tickets and T means total tickets. We know that S is two times A and T is 363. So, S will be 2x and A will be x. Then, the new equation is 2x + x = 363. 
 S + A = T 
2x + x = 363 
3x = 363 
x = 363 / 3 
x = 121 
 
Adult tickets: A = x = 121 
Student tickets: S = 2x = 2 * 121 = 242