Answer:
[tex]\boxed{\text{\$2.85/gal}}[/tex]
Step-by-step explanation:
\text{Average cost} = \dfrac{\text{Total cost}}{\text{Number of gallons}}
1. Total cost
7 gal × $2.68/gal = $ 18.76
+ 14 gal × $2.63/gal = 36.82
+ 16 gal × $3.11/gal = 49.76
TOTAL = $105.34
2. Total gallons
Total = 7 + 14 + 16 = 37 gal
3. Average cost
[tex]\text{Average cost} = \dfrac{\text{\$105.34}}{\text{37 gal}} = \textbf{\$2.85/gal}\\\\\text{The average cost for the trip was $\boxed{\textbf{\$2.85/gal}}$}[/tex]