The function f(x) = 0.85x + 3.99 models the total cost of purchasing x key chains from an Internet company that charges shipping. The function
g(x) = 1.10x models the total cost of purchasing x number of the same
key chains from an Internet company that does not charge shipping.
What is the best approximation of the number of key chains for which
the two companies charge the same amount?

14

16

15

17