Alright, lets get started.
Amy can run [tex] \frac{1}{10} [/tex] mile per minute.
Means Amy is running [tex] \frac{1}{10} [/tex] miles = 1 minute
Amy is running 1 mile = [tex] \frac{1}{\frac{1}{10}} [/tex] = 10 minute
So, Amy will run 3 miles = [tex] 10 * 3 = 30 [/tex] minutes
It means 30 minutes it will take Amy to run 3 miles. : Answer
Hope it will help :)
