Answer:
256
Explanation:
First, let's see the height of the box (8 inches) is long enough for one straw (7 inches and 3/4) but not enough for 2... so there could be only one layer.
Now the box is a prism with a square base (6 inches each side).
How many straws can we fit on one side? We have to divide the width of the box by the width of a straw.

We can fit 16 straw per 6-side side of the box... Since the box is 6x6 inches, we can then fit 16 x 16 straws in it... 256 total.