Let $\mathrm { f } ( \mathrm { x } )$

Multiple Choice

Let $\mathrm { f } ( \mathrm { x } )$ compute the time in hours to travel $x$ miles at 49 miles per hour. What does $\mathrm { f } ^ { - 1 } ( \mathrm { x } )$ compute?

A) The hours taken to travel $x$ miles at 49 miles per hour
B) The hours taken to travel 49 miles
C) The miles traveled in $x$ hours at 49 miles per hour
D) The miles traveled in 49 hours