Answer:
They are going away from each other.
So add up their speed.
combined speed = x+x-16
=2x-16
Time = 2 hours
Distance = 400 miles
Distance = speed * time
(2x-16)* 2
4x-32=400
4x=400+32
4x=432
/12
x=108 mph west bound
east bound = 108 -16 = 92 mph