Francis teaches the piano. he charges each student an enrollment fee of $100 plus $15 per hour of piano lessons. the average cost of lessons for a student per hour is $25.

I added screenshots with the complete question as well as the available choices.

25 =

which is the first option

Explanation:
We given that:
He charges $100 as enrollment fees and $15 per hour
Given that the number of hours is h, the total cost for h hours will be:
cost = 100 + 15h ...........> I

We are also given that:
The average cost per hour is $25.
This means that:
= $25 ............> II

Divide both sides of equation I by h:
=

Substitute with = 25 to get the equation used to solve for h as follows:
25 =

Hope this helps :)