Answer: 24 gallons
Check: (1/6)24=4, 4+14=18, 18/24=3/4, good
(2,0) and (-4,0) hope this helps❤️
In you question which as ask to calculate the probability that time headway is at most 6 seconds and base on my further research and analysis about the said equations and functions, I would say that the probability would be 0.15 or 15%. I hope you are satisfied with my answer and feel free to ask for more