Let's mark or variables as c = senior Citizen and S = Student.
We know that:
4c + 5s = 102
7c + 5s = 126
Elimination seems to be an easy way to solve this. So, we multiply the first equation by -1, thus eliminate the student tickets for now:
-4c - 5s = -102
7c + 5s = 126
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3c = 24
Divide both sides by 3:
c = 8
Now we can solve for c and check our work:
4 * 8 + 5s = 102
32 + 5s = 102
5s = 70
s = 14
7 * 8 + 14 * 5 = 126
56 + 70 = 126
126 = 126
So senior citizen tickets are $8 and student tickets are $14.