Question

I just need the advance ticket price iknow that the same day is 15$

Answer 1

I would feel better if you'd explain how you "know" that a "same-day" ticket is $15.  

"The combined cost of one advance ticket and one same-day ticket is $35."  This would imply that the cost of one advance ticket is $(35-15), or $10.  

Check by substitution to determine whether $15 and $10 are correct.  If not, please show your work, so that someone else or I could step back in and help.