It would be x + 5.75 because the child ticket is 5.75 less than the adult ticket so to solve how to get the adult ticket you do the opposite
The value is already in its simplest form, it cannot be reduced any further.
G=4ca-3ba <=> G=a(4c-3b)
<=> a=G/(4c-3b)
I believe the answer is A.
The other values have repeated X values.