Answer:
f(x) = 70 + 2x
Explanation:
In this problem, we first need to consider how much we get per day.
$70 is our constant.
$2 will be dependent on the number of books sold.
Here 'x' will represent the number of books sold.
f(x) = 70 + 2x
Now let's try it out.
Let's say we sold 0 books
f(0) = 70 + 2(0) = 70
This shows us that we only get our constant pay.
Now let's try for 1 or more books.
f(1) = 70 + 2(1) = 72
f(2) = 70 + 2(2) = 74
So the recursive formula f(x) = 70 + 2x is a good formula to model the situation.