[Question]: John buys a pair of earbuds that cost $200. If tax was 15%, how much did he pay after tax?
[Answer]: The tax was 200 * .15 = $30. So he paid 200 + 30 = $230.
So the answer is 230.

[Question]: The sky currently has 4 times as many cirrus clouds as cumulus clouds, and 12 times as many cumulus clouds as cumulonimbus clouds. If the sky currently has 3 cumulonimbus clouds, how many cirrus clouds are in the sky at this moment?
[Answer]: The sky has 3 * 12 = 36 cumulus clouds. The sky has 4 * 36 = 144 cirrus clouds.
So the answer is 144.

[Question]: Mara has 12 bags with 2 marbles in each bag. Markus has 2 bags with 13 marbles in each bag. How many more marbles does Markus have?
[Answer]:
Mara has 2 x 12 = 24 marbles. Markus has 2 x 13 = 26 marbles. Markus has 26 - 24 = 2 more marbles than Mara.
So the answer is 2.