Which computation could be used to find the area of the front cover of this notebook?

A. add 15 and 15 and 10 and 10

B. add 15 and 10

C. add 15 and 10 and multiply the answer by 2

D. multiply 15 by 10

The answer is D.

To get an area of any 4 sided object (like you text book), we multiply the length and the width.

All the other answers don't multiply only 2 numbers together, so we know it must be D)