Solve
-A Twin-Engined Aircraft Can Fly 816 Miles from City $51 \mathrm { mph }$

Solve.
-A twin-engined aircraft can fly 816 miles from city A to city B in 4 hours with the wind and make the return trip in 6 hours against the wind. What is the speed of the wind?

A) $51 \mathrm { mph }$
B) $68 \mathrm { mph }$
C) $17 \mathrm { mph }$
D) $34 \mathrm { mph }$