The fee for one class is $65 dollars.
To explain: x is the rate of change
The y-intercept (25) is the initial fee
y is the total cost
The fee for one class is going to involve the rate of change 40x. For each class it is $40 dollars so one class would be y=40(1)+25 which goes to y=40+25 which goes to y=65 if you add them together. One class would be $65.