Answer:
$7
Explanation:
Let a be the price of the adult ticket and s be the price of the student ticket
That means that:
2a+3s=39
and
a+2s=23
Using elimination
-2(a+2s=23)
-2a-4s=-46
-2a-4s=-46
2a+3s=39
Eliminate a:
-s = -7 ; s = 7
I probably made this so much more complicated than it should be but...