The teachers' editions of a statistics textbook sell for $150 each, and students' editions of the book sell for $50 each. Which function can be used to find the average cost per book if two teachers' editions and x students' editions are purchased?

the answer is D.

(300 + 50x) / (2 + x)

Step-by-step explanation:

Let the cost of teachers' edition books be t

Let the cost of students' edition books be s

So t = 150; s = 50

Then the total cost of 2 teachers' editions and x students' editions is 2t + sx = 2 * 150 + 50x = 300 + 50x.

The total number of books is 2 + x.

So the average cost per book is (300 + 50x) / (2 + x)