Let's set up variables and equations for things that we know from the question, with a standing for advance tickets, and s standing for same day tickets.
Let's solve it through substitution. Isolate either variable, a or s. I'll choose to isolate a. Subtract s from both sides.
Plug the new knowledge into the first equation, since we now know the value of a
.
Distribute the 40 to the -s and 35
Combine the negative and positive s
Subtract 1400 from both sides.
Divide both sides by -10
The total price of an advanced ticket and same-day ticket is 35, and we know the value of a same-day ticket, so the price of an advance ticket must be 20.
The final answers are:
advanced ticket = 20
same day ticket = 15