For future reference, if you need assistance that requires in-depth explanation, I would encourage you to make a tutoring appointment to make sure you can grasp the concepts. Here are my quick answers to your questions:
Question 1: You have a piecewise function which allows for different functions of y at different intervals of x. In this case, your top function (1/4)x2 + 1 includes the values for X < 3, and this means when x =3 or when x is less than 3. So, it is your answer, Choice A.
Question 2: This is simply a matter of reading the question properly. You have 625 students to start with, all paying a $400 course fee. This means your top rows must have $400 in the first row of the first column, and 625 in the first row of the second column. Immediately, you can eliminate options A and B.
Remember that if the fee decreases by $20, the student population increases by 50. This leaves only one option, Choice D.