Answer
$B∪D = \{ 4,6,1,3,5,7,9,........\}$
Work Step by Step
$B = \{x|x$ is an odd integer $\} $
$B= \{1,3,5,7,,9,...... \}$
$D= \{ 4,5,6,7 \}$
$B∪D = \{ 4,6,1,3,5,7,9,........\}$
$B∪D = \{x|x$ is an odd integer or $x = 4 $ or $ x = 6\} $