The first thing you should know is the following conversion:
1h = 60min
What you can do to solve the problem is the use of a rule of three:
60 ---> 3.8
165 ---> x
Clearing the value of x we have:
x = (165/60) * (3.8) = 10.45
x = 10.45 mi
answer
she can walk 10.45 mi in 2 hours 45 minutes