If you walk for 45 minutes at a rate of 4 \mathrm{mph} and then run for 30 minutes at a rate of, 10 \mathrm{mph}, how many miles have you gone at the end of one hour and 15 minutes?
Answer Choices
A. 3.5 miles
B. 8 miles
C. 9 miles
D. 25 \dfrac{1}{3} \mathrm{miles}
E. 480 \mathrm{mIles}