Solve the Problem $3 \mathrm{mph}$ Walking And $4 \mathrm{mph}$ Jogging the Distance from His Home to the Coffee Shop

Solve the problem.
-James walks and jogs to his favorite coffee shop to study each weekend. He averages $3 \mathrm{mph}$ walking and $4 \mathrm{mph}$ jogging. The distance from his home to the coffee shop is $13 \mathrm{mi}$ , and he makes the trip in $4 \mathrm{hr}$ . How long does James jog?

A) $2 \mathrm{hr}$
B) $1 \mathrm{hr}$
C) $4 \mathrm{hr}$
D) $3 \mathrm{hr}$