Question

if you are driving at a rate of 55 miles per hour, about how man feet per second are you traveling

Answer 1

I believe you are travelling about 81 (80 and 2/3 to be exact) feet per second.

Answer 2

There's a pertinent identity:  60 mph = 88 ft/sec.

Thus,

55 mph     88 ft/sec

------------ * -------------- = 80.1 ft/sec

      1           60 mph