Answer:
Price of a senior citizen ticket is $4 and price of a student ticket is $15 .
Step-by-step explanation:
Let us assume that the price a senior citizen ticket be x .
Let us assume that the price a student citizen ticket be y .
As given
The school that Jack goes to is selling tickets to a choral performance.
 On the first day of ticket sales the school sold 9 senior citizen tickets and 8 student tickets for a total of $156.
Equtaions becomes 
9x + 8y = 156 
As given
The school took in $163 on the second day by selling 7 senior citizen tickets and 9 student tickets.
Equations becomes 
7x + 9y = 163 
Multipy 9x + 8y = 156 by 9 .
81x + 72y = 1404 
Multiply 7x + 9y = 163  by 8 .
56x + 72y = 1304 
Subtracted 56x + 72y = 1304 from 81x + 72y = 1404 .
81x - 56x + 72y - 72y = 1404 - 1304 
25x = 100

x = $ 4 
Putting value of x in the 56x + 72y = 1304 .
56 × 4 + 72y = 1304 
224 + 72y = 1304 
72y  = 1304 - 224 
72y = 1080
 
y = $15
Therefore the price of a senior citizen ticket is $4 and price of a student ticket is $15 .