Final answer:
The equation that expresses the total cost in terms of the number of students in a class is C = 50 + 20x, where C is the total cost and x is the number of students in the class.
Step-by-step explanation:
The equation that expresses the total cost in terms of the number of students in a class is:
C = 50 + 20x
where C is the total cost and x is the number of students in the class. The fixed cost is $50 (the y-intercept) and for each student, an additional $20 is added to the cost (the slope).