Chapter 2 Linear Equations and Functions - 2.4 Write Equations of Lines - 2.4 Exercises - Problem Solving - Page 104: 55

See below.

The average yearly increase was $\frac{38.23-21.62}{2004-1994}=\frac{16.61}{10}=1.661$. Thus the equation (if the years passed since 1994 is $x$) is: cost$=21.62+1.661x$. Hence at 2010, $x=16$, thus: cost$=21.62+1.661\cdot16=48.196$.