Solve
-Khang and Hector Live $40.8$ Miles Apart in Southeastern Missouri $70 \%$

Solve.
-Khang and Hector live $40.8$ miles apart in southeastern Missouri. They decide to bicycle towards each other and meet somewhere in between. Hector's rate of speed is $70 \%$ of Khang's. They start out at the same time and meet 4 hours later. Find Hector's rate of speed.

A) $24 \mathrm { mph }$
B) $6 \mathrm { mph }$
C) $4.2 \mathrm { mph }$
D) $40.8 \mathrm { mph }$