A company builds computers. It costs $6,700 to build 10 computers and $12,200 to build 20 computers. Which equation models the cost, C(x), as a linear function of the number of computers built, x? C(x) = 550x −1200 C(x) = 550x + 1200 C(x) = 1200x − 550 C(x) = 1200x + 550