Trevon's school is selling tickets to a musical. On the first day, the school sold 3 senior tickets and 2 child tickets resulting in $37. The school took in $134 on the second day by selling 12 senior tickets and 7 child tickets. Find the price of a senior ticket and the price of a child ticket.

3s+2c=37
12s+7c=134
To solve we need to multiply the first equation by negative 4
-4(3s+2c=37)
-12s+-8c=-148
12s+7c=134
Cross out the 12s on the two above equations.
-c=-14
c=14
Now let’s plug in value c to first original equation :
3s +2(14)=37
3s+28=37
3s=9
s=3
To recap: senior tickets cost $3 each; children tickets cost $14 each