The gray area is the sidewalk. the area of the sidewalk is square units.

Morris is traveling at 48 mph.

Step-by-step explanation:

You may know the identity 88 ft/sec = 60 mph.  Using this makes the solution of this problem relatively easy.

First, we'll convert 50 mph to ft/sec:

50 mph           88 ft/sec

* = 73.3333 ft/sec

1 sec                 60 mph

So, Aneesha is traveling at 73.3333 ft/sec.  Morris is traveling 3 ft/sec slower, which works out to  70.3333 ft/sec.  We have to convert this back to miles per hour:

70.3333 ft/sec        60 mph

* = 47.95 mph, or 48 mph (Answer D)

          1                     88 ft/sec