1.25j+5.25 would be the answer. just combine like terms
So the ration is 1 to 5 since it's one foot every 5 seconds. So for every 5 seconds, add 1 foot.
For example: in 45 seconds, it would travel 7 feet.
But in this Scenario, the timer starts after 5 feet so just add 5
Ex. in 45 seconds, it would have traveled 12 feet since we added the 5 feet that we started with to the 7 other feet it traveled.
Idk If this will help very much but I hope it does.
Therefore 
Step-by-step explanation:
Given,
Therefore
