Known: Gas tank holds 17.5 gal and Peter uses 2/3 gallon per 20 minutes of off-road driving.
Questions:
1) How much gas is left after 2 hours?
2) How long before Peter runs out of gas.
Lets rephrase the gas consumption as gallons/hr.
2/3 gal per 20 minutes is the same as 6 gal/hr (multiply by the conversion factor 60 min/1 hr)
(2/3 gal/20 min) x (60 min/1 hr) = 2 gal/hr
After 2 hour, 4 gallons of gas are consumed [2 hr * 2 gal/hr = 4 gal].
Subtract from the original 17.5 gallons. 17.5 gal - 4 gal = 13.5 gal after 2 hours.
Peter will run out of gas according to:
17.5 gal = 2 gal/hr * X hours
or X = 8.75 hours [in 8,75 hours at 2 gal/hr, the gas consumption will be 17.5 gallons and Peter will be out of cell range. Maybe as he's walking out, he'll can look for X.
