This can be solved using a system of equations.

Subtract y from both sides.

Substitute:

Subtract 80 from both sides:

Divide both sides by 5:

Substitute.
Answer:
The index of refraction of the second medium is higher.
Step-by-step explanation:
Slope equals rise over the run
so if slope = 5 then the rise also equals 5 and the run is 1
1st: add 5 to each side
2nd: divide by 2 on each side