When the moving sidewalk at the airport is broken, as it often seems to be, it takes you 44 s to walk from your gate to baggage claim. When it is working and you stand on the moving sidewalk the entire way, without walking, it takes 90 s to travel the same distance

a) 29.55 sec

Explanation:

Let the total distance be s feet.

Speed while walking = s/44 ft/sec.

Speed on sidewalk = s/90 ft/sec.

Total speed while walking on moving sidewalk

= s/44+s/90 = (90s+44s) / 44*90

= (134x) / 3960 ft/sec

= x/29.55 ft per sec.

Hence your travel time will be 29.55 secs.