#### Answer

$20$

#### Work Step by Step

Using the diagram gives:
$n(B)=3+10+5+2=20$

Published by
Pearson

ISBN 10:
0-32193-104-1

ISBN 13:
978-0-32193-104-7

$20$

Using the diagram gives:
$n(B)=3+10+5+2=20$

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