simple question need clarification

[grandh01]

The Earth travels around the Sun at a
speed of approximately 18.5 miles per
second. This approximate speed is how
many miles per hour?
(A) 1,080
(B) 1,160
(C) 64,800
(D) 66,600
(E) 3,996,000

clarification

[theCEO]

18.5miles x 60sec x 60min
---------------------------- = 66,600miles/hr
1sec x 1min x 1hr

[spoiler]ans = d[/spoiler]