The answer is y=22 I think
Well let's see what floor each one lands on and figure out which one is higher.
Something to note:
down = subtracting
up = adding
if something says it's doing something more than once, add it the number of times it's doing that thing. (You can also multiply it by that number but the adding way is a bit easier to understand and explain)
<u>Elevator 1:</u>
6 + 7 + 7 - 10 = 10
<u>Elevator 2:</u>
20 - 5 - 5 - 5 + 12 = 17
Elevator 2 ends on a higher floor (reasoning above)
The two equations are

and

the first equation can be solved for x to be

next you can substitute x in the second equation

Distribute 4 to everything in the parentheses

combine like terms:

subtract 28 from both sides of the equation

divide both sides by -1.5

plug this in to the original equation of x+y=7

subtract 4 from both sides.

Final Answer: they bought 3 adult tickets and 4 student tickets
Hope this helps!
4000. 25000 x .16 is 4000