We can form two equations, let the price of a senior ticket be s and the price of a child ticket be c.
We have from day 1:
A: 3s + 9c = 75
And from day 2:
B: 8s + 5c = 67
Now we can rewrite A as:
A: 24s + 72c = 600
And can rewrite B as:
B: 24s + 15c = 201
Now A-B can be written as:
A-B: 57c = 399
So c = 7
Now substituting this back into A we get:
A: 3s + 63 = 75
A: 3s = 12
So s = 4
We have the price of a senior ticket is $4 and the price of a child ticket is $7 (idk if this is right hope it is!!!)