One Morning, John Drove 6 Hours Before Stopping to Eat $\quad 33 \mathrm { mph }$

Multiple Choice

One morning, John drove 6 hours before stopping to eat.After lunch, he increased his speed by 10 mph. If he completed a 390-mile trip in 9 hours of driving time, how fast did he drive in the morning?

A) $\quad 33 \mathrm { mph }$
B) $\quad 36 \mathrm { mph }$
C) $\quad 48 \mathrm { mph }$
D) $\quad 43 \mathrm { mph }$
E) $\quad 40 \mathrm { mph }$