Answer:
There are 714 total stamps.
Explanation:
Daniel has 102 stamps, so 102 is our first number.
Manuel has 2x as many stamps as Daniel (who has 102) so we do...
102 x 2 = 204
204 is our second number.
Kendra has 2x as many as Manuel (who has 204).
204 x 2 = 408
408 is our third number.
Now we add the three stamp numbers together to get the total:
102 + 204 + 408 = 714
There are 714 total stamps.