#### Answer

$a_1=8$
$d=5$

#### Work Step by Step

In an arithmetic sequence, the common difference can be calculated as the difference of any two subsequent terms:
$d=a_2-a_1=13-8=5$
The first term is:
$a_1=8$.

Published by
Pearson

ISBN 10:
0-32184-874-8

ISBN 13:
978-0-32184-874-1

$a_1=8$
$d=5$

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