lets say y is number of adult tickets and x is number of student tickets
x+y=348
2x+y=348
(2x since I know that the student tickets are twice as much as adult tickets)
I now know that that student tickets make up 2/3 of the total number of tickets and 1/3 make up the number of adults tickets. So...
1/3 x 348= 116 adult tickets
2/3 x 348=232 student tickets