Chapter 3.2, Problem 19E

Find the determinants in Exercises 15–20, where

$\left|\begin{array}{ccc}\text{a}& \text{b}& \text{c}\\ \text{d}& \text{e}& \text{f}\\ \text{g}& \text{h}& \text{i}\end{array}\right|=7.$

19. $\left|\begin{array}{ccc}\text{a}& \text{b}& \text{c}\\ \text{2}\text{d+a}& \text{2}\text{e+b}& \text{2}\text{f+c}\\ \text{g}& \text{h}& \text{i}\end{array}\right|$