Question 133087
First question. how many miles per gallon will the truck go at 60mph?

The problem tells us that the truck gets 30% poorer mileage at 60mph than it does at 50mph. It gets 20mpg at 50. 30% of 20mpg is 6mpg. So the truck makes (20-6)mpg at 60. --> Use 14 miles per gallon at 60. 

In order to go 160 miles, we would need {{{160 / 14 }}} gallons of gas.
That is 11.43 gallons.

The tank is only 10 gallons, so we will need to refuel at the 140 mile marker

total time will be the time it takes to drive 160 miles at 60mph + 1 fuel sto
{{{160/60}}} is 2.666 hours driving = 2 hours 40 minutes.
Add in one fuel stop of 20 minutes.
Total time is 3 hours