Day 1: a + 11s = 68
Day 2: 13a + 5s = 194
Rewrite Day 1 to isolate a, then substitute the value of a into Day 2. You now have one variable to solve for.
Day 1: a = 68 - 11s
Day 2: 13 (68-11s) + 5s = 194
884 - 143s + 5s = 194
138s = 690
s = 5
Student tickets cost $5 each.
You can now substitute the 5 for s into the original equations to find the cost of an adult ticket.
a + 55 = 68
a = 13
13a + 25 = 194
13a = 169
a = 13
Adult tickets cost $13 each.
