#### Answer

The top two layers are 10.9 cm thick,

#### Work Step by Step

The top layer is 64mm. Convert to cm by moving the decimal.
$64mm=6.4cm$
Add the depth of the top two layers.
$6.4cm+4.5cm=10.9cm$

Published by
Pearson

ISBN 10:
0134467795

ISBN 13:
978-0-13446-779-5

The top two layers are 10.9 cm thick,

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