Final answer:
The answer is 3240 pens.
Explanation:
To find the total number of pens Tina bought, you multiply the number of boxes by the pens in each box:
36 boxes x 90 pens/box = 3240 pens
Therefore, Tina bought 3240 pens in total.
Learn more about Calculating the total number of items in a purchase here:
https://brainly.com/question/43848544
