This is a proportion problem, and the answer is
[tex] 15 {\textrm{ miles}} \times \dfrac{28 \textrm{ minutes}}{8 {\textrm{ miles}}} = \dfrac{105}{2} = 52.5 \textrm { minutes}[/tex]
8 miles = 28 minutes
1 mile = 28 ÷ 8 = 3.5 minutes
15 miles = 3.5 x 15 = 52.5 minutes
Answer: 52.5 minutes
