## Elementary Geometry for College Students (6th Edition)

$EC=12$
The parallel line that crosses through the triangle creates proportional sides in the triangle. Or, in other words... $\frac {AD}{DB}=\frac {AE}{EC}$ Substitute in known values, and $x$ for the unknown value... $\frac{6}{8}=\frac{9}{x}$ Cross Multiply... $6x=8(9)$ $6x=72$ Divide both sides by six... $x=12$ or $EC=12$