Answer
(a) $20$ gallons
(b) $[1,2.9]$
Work Step by Step
(a) We see from the graph that there were $20$ gallons of gasoline in the tank at $x=3$ (3 hours).
(b) We see from the graph that the steepest slope occurs between $t=1$ and $t=2.9$ (right before 3). Thus the car burned gas at the fastest rate on the interval $[1,2.9]$.
