What is the formula to use for this question, "how far does light travel in 2.5s"?

The definition of the speed of light is exactly 299,792,458 meters per second, so to find how far it travels in a time period, multiply the speed of light times the time. Aka c=299,792,458m/s where c is speed of light, m is meters, and s is seconds. So for example to find how far light travels in 5 seconds, multiply by 5.

678,408

Explanation:

Thank you for posting this incredibly challenging problem. It is questions like these that stimulate the mind and lead to educational development.

;)